# Dodge Ram 1500



## Dads3girls

I just bought a 2007 Dodge Ram 1500 Crew Cab with the 5.7 Hemi and 3.92 gear ratio.
The dealer info says it has a towing capacity of 9,850 lbs.
I also just bought a 2007 28RSDS with a dry weight of just over 6,000 lbs.
I have a WD kit that will be installed with 800 lbs rating on the bars and an friction sway bar.
This is the first time with a larger truck and larger trailer.
Can anyone tell me what to expect.


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## CamperAndy

Long Bed or Short? Wheelbase makes a difference. Did it come with the 17 or 20" wheels? It is a 1000 pound hit on your towing if it is 20".

On the flats you will be fine but you will hate to watch the gas gauge when you get into the mountains. If the Weight distribution hitch is still in the box ask the dealer if he will take it back for a better hitch and one with a slightly higher weight bars. You want 1000 pound bars for your trailer and you want either a Straight-Line Dual cam or Equal-i-zer hitch.


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## Dads3girls

I have the short bed with 20" wheels.
After reading this site I plan on increasing to 1000-1200# bars. The max payload for the truck is 1,330#. The tongue weight of the trailer is 745#. With the gas tanks and batteries, this would add another 1-200#.
Any more thoughts?


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## rock hill

I believe a single friction anti-sway bar is only good for trailers up to 25 feet, after that it is recommended that you
have two of them, one on either side.


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## Nathan

Dads3girls said:


> I just bought a 2007 Dodge Ram 1500 Crew Cab with the 5.7 Hemi and 3.92 gear ratio.
> The dealer info says it has a towing capacity of 9,850 lbs.
> I also just bought a 2007 28RSDS with a dry weight of just over 6,000 lbs.
> I have a WD kit that will be installed with 800 lbs rating on the bars and an friction sway bar.
> This is the first time with a larger truck and larger trailer.
> Can anyone tell me what to expect.


I'd strongly suggest something better than a Friction sway bar. The 28RSDS is a long trailer and needs a more effective sway solution. Get either and Equal-I-Zer brand hitch or a Reese Dual Cam (aka Straight Line) hitch.


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## Nathan

Dads3girls said:


> I have the short bed with 20" wheels.
> After reading this site I plan on increasing to 1000-1200# bars. The max payload for the truck is 1,330#. The tongue weight of the trailer is 745#. With the gas tanks and batteries, this would add another 1-200#.
> Any more thoughts?


X2 on what Andy said. Expect the tounge weight to be right about 1000 lbs when loaded to go.


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## Duanesz

3.92 Gears and all that power it should tow good. Just get your setup right and add fuel.


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## CamperAndy

Duanesz said:


> 3.92 Gears and all that power it should tow good. Just get your setup right and add fuel.


The over sized wheels (20" compared to stock 17") actually knock the effective ratio back to about 3.50 and that hurts the towing rating by 1000 pound per Dodge.


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## Dads3girls

CamperAndy said:


> 3.92 Gears and all that power it should tow good. Just get your setup right and add fuel.


The over sized wheels (20" compared to stock 17") actually knock the effective ratio back to about 3.50 and that hurts the towing rating by 1000 pound per Dodge.
[/quote]
Even on short hauls...say less than a 3 hours trip?
The tow rating is 9,800#, so you are saying the 20's lower it to 8,800#?
The trailer dry is just over 6,000#
Should I buy 17" rear wheels? The 20's come stock to the truck, does that matter?


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## CamperAndy

Even on short hauls it matters but you still have a little room in what you can tow. Also never use the dry weight for calculations as no one tows empty or dry. Use the gross weight of the trailer to see where you are.

As for the wheels being stock. That is how I know it is a hit on towing. I had a 2005 1500 with the same set up. Also does it have 4x4? That is also a hit on towing as the curb weight goes up over the "Brochure" model where they quote such a massive towing rating for a 1500.

If you replace the wheels, you have to replace them all.


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## Duanesz

Overall tire height is what kills the ratio. How much taller is a 20" wheel truck than a 17" wheel set up? Does the 07 ram have a 4 speed trans? My buddy's wife had a durango 5.? Hemi. That thing had all kinds of power and towed a enclosed snowmobile trailer awesome.


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## Carey

The 20 inch wheels are only spec'd with 3.92 rear gear ratio.
The 17 inch wheels are only spec'd with 3.55 rear gear ratio.

Unless special ordered with the 3.92 rear gear and 17 inch wheels. Very few trucks came with 17 inch wheels and a 3.92 ratio.

The 20 inch wheels use a 33 inch tall tire. 
The 17 inch wheels use a 31.7 tall tire.

This is what the rear end gears feel like when comparing the two against each other. I call this the feel gear. This is a comparasion of the gears and tire sizes.

20 inch wheels with 3.92 rear gear = 3.77 ratio
17 inch wheels with 3.55 rear gear = 3.70 ratio

Dodge allowed the extra .7 tenths to allow the make up of static loss in rolling mass to be equal to a 17 inch wheels with a 3.55 ratio.

Lets say your final transmission ratio is 1 to 1.

Your rpms with 20 inch wheels 33 tall tires and 3.92 gears is 2588
Your rpms with 17 inch wheels 31.7 tall tires and 3.55 gears is 2405

For each pound of rotating weight you lose, it's equivalent to losing 10 lbs of static weight in terms of performance and mileage. 20 inch wheels and tires are heavier than 17 inch tires and wheels. Dodge factored this into to the gear choice.

Since the 20 inch wheels and tires are heavier, dodge specs a bit lower gear to make up the difference with the 17 inch wheel and tire combo to equal static and rolling mass differences and tire height bewteen the 2 vehicles.

People say that using 20 inch wheels create a 5-1000 towing loss. Ive seen people mention both.

This is a flat out myth. Know where in the towing guides or any published specification manual does it ever mention that using 20 inch wheels cause a towing loss.

Every pick up manufacturer offers a small base wheel and a larger upgraded wheel. Every manufacturer then makes the final gear ratio changes to make the both at an exact equal when comparing feel, mass, static weight, performance and fuel mileage. Since the wheels are engineered to the gear. Tow rating remain the same between the two models because of the engineering changes that have been made to make both vehicles equal.

Carey


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## CamperAndy

Colorado~DirtBikers said:


> People say that using 20 inch wheels create a 5-1000 towing loss. Ive seen people mention both.
> 
> This is a flat out myth. Know where in the towing guides or any published specification manual does it ever mention that using 20 inch wheels cause a towing loss.
> 
> Carey


I didn't make it up Carey, 2004 tow ratings, See item "K" for the 1500 and compare to the same without. If you don't trust this source then it would be great if the manufactures would have their own comprehensive tow guide.


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## Carey

If you switch to a 17 inch wheel with 31.7 tall tires your effective rear gear ratio would be 4.08. This would be an add of about 100 rpms across the board.


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## Carey

CamperAndy said:


> People say that using 20 inch wheels create a 5-1000 towing loss. Ive seen people mention both.
> 
> This is a flat out myth. Know where in the towing guides or any published specification manual does it ever mention that using 20 inch wheels cause a towing loss.
> 
> Carey


I didn't make it up Carey, 2004 tow ratings, See item "K" for the 1500 and compare to the same without. If you don't trust this source then it would be great if the manufactures would have their own comprehensive tow guide.
[/quote]

Yes Ive seen that only for 2004. This was a mistake made back then. Know where after 2004 does it say that using a 20 inch wheel cause a towing loss.


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## CamperAndy

Colorado~DirtBikers said:


> People say that using 20 inch wheels create a 5-1000 towing loss. Ive seen people mention both.
> 
> This is a flat out myth. Know where in the towing guides or any published specification manual does it ever mention that using 20 inch wheels cause a towing loss.
> 
> Carey


I didn't make it up Carey, 2004 tow ratings, See item "K" for the 1500 and compare to the same without. If you don't trust this source then it would be great if the manufactures would have their own comprehensive tow guide.
[/quote]

Yes Ive seen that only for 2004. This was a mistake made back then. Know where after 2004 does it say that using a 20 inch wheel cause a towing loss.
[/quote]

I would not call it a mistake. You know there is a cost for every change in the drive line. 2004 was the first year of the 20" wheels and you could get them both ways 17" or 20" with the 3.92 gears and a direct comparison was there. After 2004 the 20" was standard and maybe would not have been a separate tow rating and thus you would not have seen the loss. If it were true that 20" wheels were not a hit on towing then I am sure you will be going to some nice big 35's when you get some new wheels. Lower RPM means better mileage and that is what you want towing commercial isn't it and since taller tires don't hurt your tow rating.

Sorry for the attitude but the rating system for our trucks is far to driven by marketing and not by engineering.


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## Carey

As far as what the allowable weight allowed on the tires.

275/60/20 have a max rating of 2601 lbs
265/70/17 have a max rating of 2535 lbs

Dodge has engineered all the required changes to make both vehicles equal with each other.


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## CamperAndy

Dads3girls said:


> I just bought a 2007 Dodge Ram 1500 Crew Cab with the 5.7 Hemi and 3.92 gear ratio.
> The dealer info says it has a towing capacity of 9,850 lbs.
> I also just bought a 2007 28RSDS with a dry weight of just over 6,000 lbs.
> I have a WD kit that will be installed with 800 lbs rating on the bars and an friction sway bar.
> This is the first time with a larger truck and larger trailer.
> Can anyone tell me what to expect.


Jeff since this has gotten deeper into the tow rating of the truck (which I still think has plenty) the number you were given is wrong. there are no 2007 1500's rated at 9,850. The highest rated truck is 8,700 pounds, 2007 tow ratings. Which dealer told you it was 9,850? Dodge or the trailer salesman?


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## Carey

CamperAndy said:


> People say that using 20 inch wheels create a 5-1000 towing loss. Ive seen people mention both.
> 
> This is a flat out myth. Know where in the towing guides or any published specification manual does it ever mention that using 20 inch wheels cause a towing loss.
> 
> Carey


I didn't make it up Carey, 2004 tow ratings, See item "K" for the 1500 and compare to the same without. If you don't trust this source then it would be great if the manufactures would have their own comprehensive tow guide.
[/quote]

Yes Ive seen that only for 2004. This was a mistake made back then. Know where after 2004 does it say that using a 20 inch wheel cause a towing loss.
[/quote]

I would not call it a mistake. You know there is a cost for every change in the drive line. 2004 was the first year of the 20" wheels and you could get them both ways 17" or 20" with the 3.92 gears and a direct comparison was there. After 2004 the 20" was standard and maybe would not have been a separate tow rating and thus you would not have seen the loss. If it were true that 20" wheels were not a hit on towing then I am sure you will be going to some nice big 35's when you get some new wheels. Lower RPM means better mileage and that is what you want towing commercial isn't it and since taller tires don't hurt your tow rating.

Sorry for the attitude but the rating system for our trucks is far to driven by marketing and not by engineering.
[/quote]

No just by having lower rpm does not make things better as far as fuel mpgs are concerned.

Its a HUGE mix of engineering built into the vehicle.

If you lower your rpms from where the vehicle is set at from the factory, you are creating more grind in the driveline and engine. The vehicle will need to be able to handle this grind that you have added to it. Grind equals heat and possible added wear. IF the vehicle can handle this you might gain some fuel mpgs by lowering rpms.

You said, If it were true that 20" wheels were not a hit on towing then I am sure you will be going to some nice big 35's when you get some new wheels.

If you made the required changes to the gearing this could be done to make the vehicle feel equal with either 33 or 35 tall tires.

The engineers at dodge made the proper changes between the vehicles that have either 17 or 20 inch wheels to make them at an equal with each other.

Yes, the 20 inch wheels are heavier and this cant be made up by gearing. A fuel mpg loss will been encountered no matter what gearing is choosen because of the static rolling mass is now more. BUT this addition of mass can be easilly overcome by the drivetrain so the driver does not feel the differences in mass between the two.

No, lower rpms are only a help IF the vehicle can take having the lower rpms. If it cant you will lower the life expectancy of any commercial vehicle. And again this is decided by a mash of gearing, tire choice, peak tq, peak hp. feel, rolling mass, static weight, and fuel mpgs. There is more here but this is the popular stuff.

Carey


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## Carey

CamperAndy said:


> I just bought a 2007 Dodge Ram 1500 Crew Cab with the 5.7 Hemi and 3.92 gear ratio.
> The dealer info says it has a towing capacity of 9,850 lbs.
> I also just bought a 2007 28RSDS with a dry weight of just over 6,000 lbs.
> I have a WD kit that will be installed with 800 lbs rating on the bars and an friction sway bar.
> This is the first time with a larger truck and larger trailer.
> Can anyone tell me what to expect.


Jeff since this has gotten deeper into the tow rating of the truck (which I still think has plenty) the number you were given is wrong. there are no 2007 1500's rated at 9,850. The highest rated truck is 8,700 pounds, 2007 tow ratings. Which dealer told you it was 9,850? Dodge or the trailer salesman?
[/quote]

Its really not deep at all.

Dodge has engineered both vehicles to be equal to each other as far as capabilities.

You are still better off using the 20 inch wheel with 3.92 ratio versus the 17 inch 3.55 combo. This is our standard choice after 2005.

After 2005 dodge requires that you special order 3.92 gears with 17 inch tires. Yes this would be the better choice to have. You are gonna be hard pressed to find this though on used trucks.

Carey


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## Bennitt5

Just to throw in my 2 cents I would call dodge and give them your vin number and they can tell you exactly what the truck was rated for. I have done this with my 2004 1500 quad cab with the 5.7l hemi. I have hauled my last two campers with the 1500 one was 30ft and the other was 32ft. my last truck could haul them fine but I never missed a gas station. I just upgraded to an 07 with the 6.7L diesel and I would never go back. They are a world apart.


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## Carey

Semis and diesels can benefit from lower rpms when towing.

A gas engine will benefit using higher rpms when towing.

Its all about torque and at what rpm that its peak is made at.

Semis can do 1300 rpms down the highway for optimum towing. They make 2000 ft lbs torque. Peak torque is 1400. peak hp is also 1400 rpms.

A dodge cummins can do 1800-2000 rpms down the highway, they make 600-700 torque. Peak torque is 1600, but peak hp is like 2900. So the engine needs to be run slightly past peak torque to keep the engine cool.

A gas engine needs 2300-2500 rpms rolling down the highway for optimum towing. They make 350-500 torque, but with any gas engine, the torque doesnt really come in until 2500 rpms and beyond up to around 4400. Peak hp is around 4000 rpms also. The toque curve is much flatter then the hp curve, so a gas has to be run to allow the engine to make a fair amount of hp to keep it cool.

In the old days gas engines didnt make alot of torque till above 3200 rpms or so. They had to be kept at around 3000 rpms for optimal towing because peak hp was closer to 5000 rpms. We are talking small blocks here cause thats whats in a new dodge.

The bigger engines of yester year could be ran lower rpms, but cooling engineering was not even close to what todays cooling engineering is. So they also were run in the 3000 rpm range.

With the electronics and fuel injection uses in todays gas engines. Our gas engines can tow at 2300 rpms and live a happy life. With new changes like the ecoboost technolgy that ford is bringing about, the final gear ratio can be changed to possibly allow lower towing rpms.

Now this is getting deeper into the subject... I could write all day about how our vehicles are engineered to preform with certain tire and wheel combos and gearing choices to make them optimal.

Its sure not just about lower rpms. Many choices must be chosen and decided on to create a perfectly balanced mash. And I can guarantee you, dodge engineers have spent a lot of time and money to make that 20 inch wheel choice as optimal as the 17/3.55 choice.


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## rdvholtwood

Bennitt5 said:


> Just to throw in my 2 cents I would call dodge and give them your vin number and they can tell you exactly what the truck was rated for. I have done this with my 2004 1500 quad cab with the 5.7l hemi. I have hauled my last two campers with the 1500 one was 30ft and the other was 32ft. my last truck could haul them fine but I never missed a gas station. I just upgraded to an 07 with the 6.7L diesel and I would never go back. They are a world apart.


In PA, the tow rating is on the title.


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## Nathan

Carey,

I'm a little confused what heat we are talking about? Are you referring to piston temps, cylinder head temps, exhaust temps, oil temps, coolant temps??

Engine operating speed is set by a fuel economy/performance tradeoff with the limitation that you have a fixed number of gears in the transmission. As # of gears go up, the engine speed at cruise can drop because you are still able to get good performance tradeoff between acceleration, and fuel economy.

Perhaps we should re-direct to the OP question.


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## CamperAndy

Nathan said:


> Perhaps we should re-direct to the OP question.


Nah, I started it.


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## Carey

Nathan said:


> Carey,
> 
> I'm a little confused what heat we are talking about? Are you referring to piston temps, cylinder head temps, exhaust temps, oil temps, coolant temps??
> 
> Engine operating speed is set by a fuel economy/performance tradeoff with the limitation that you have a fixed number of gears in the transmission. As # of gears go up, the engine speed at cruise can drop because you are still able to get good performance tradeoff between acceleration, and fuel economy.
> 
> Perhaps we should re-direct to the OP question.


Ok lets say I have a gas 1/2 ton dodge. Lets say it weighs 13000 gross. Lets say it was spec'd to run at 2300 rpms at 65mph. Lets say it has 32 inch tires. This where the factory has set the engine/driveline to be run to tow the max weight of 13000 gross.

Weight now remains the same as I make examples below.

Now I switch to 34 inch tires. The engine now runs 2100 at 65mph. Yes the entire engine will run hotter as its loaded more. Do you see this on the guage prolly not. If you measured oil temps you would though. You will see a mpg loss too.

Now take the same truck, lets put on say 30 inch tires. The engine now runs 2500. You will see a fuel mpg loss because of the higher rpm, but not as much as having the taller tires. The engine will run cooler because less load is placed on it. Most likely even the water temp gauge will show the cooler temps.

The driveline temps will also change with rpm changes. Lets say you have an automatic. It is designed to have the input speed be 2300 rpms at say 65mph. It now has the input speed set at 2100 from the taller tires. This will increase temps in the trans because of the amount of leverage has been increased behind the transmission, plus we have lowered incoming rpm which lowers rotational speed in the trans and gearing speed in the trans. Because of all these factors the trans runs hotter.

Now lets put 30 tall tires behind the tranny. Input speeds are now 2500. The leverge behind the trans has been decreased. This allows the trans to run at a cooler temp over factory settings. YES you can now tow more weight!

Basically the factory has taken many, many physics, gears, rpms etc.etc into effect here.

The dodge truck with 20 inch wheels and 33 tall tires with 3.92 gearing allows the engine to be turned slighly higher than the dodge truck with 17 inch wheels and 31.7 tall tires with 3.55 gearing.

This allows the truck to tow the same as the 17 inch wheel/3.55 equipped truck because the leveage factor behind the trans is being made up by engine rpm, input and gearing speeds inside of the transmission. Since the engine speed has been increased slightly over the 17/3.55 combo, the engine temps will remain the same for either. A fuel mpg loss will be encounterd with the 20 inch/33 tall tires because they add rotational weight. No matter what gearing choice is made we cant make up rotatioanal weight.

As for feel, the larger leverge factor loss from 20 inch wheels can be made up by spinning the engine/driveline slightly faster. This allows the driver to have 20 inch wheels without feeling he has lost performance.

BUT when one changes to a taller tire without changing gearing to match the loss in leverge/gearing, engine/trans temps rise, because of the loss of leverge/gearing your rpms will be reduced, the performance and fuel mileage expectations will be reduced because of the added grind you have placed on the engine/driveline.

The factory spsnds a lot of time finding the proper meshes to keep the vehicle at a balanced mix to control heat, wear and still get the best mpgs and emissions from the vehicle.

They have made sure that the 20 inch/3.92 combo is similar to the 17/3.55 combo. This way they can offer either choice as a standard option. Since all of the effective meshes have been made a customoer can choose either and have the same towing allowance arragement. Yes the customer can special order different final gear/wheel changes, but few ever do. People buy on looks and what fits the pocketbook. Dodge has made sure that a customer can have either and not affect there trailer towing abilities. Yes kuddos to dodge! lol

IF you set down and do the math with each manufacturer you will find that every mfr at least takes a stab at this to keep tow ratings and all of the other factors involved to allow a similiarity across there lines.

BUT again. One can order different gearing and wheel sizing on there own.

I could keep writing but I got stuff to do today. This morn I have been chasin parts. Now I got to get out there and do some work.

Carey


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## CamperAndy

Carey, set fuel economy aside. I sent you on that wild goose chase. The issue is towing capability. When comparing the same truck and drive line and you go from 17 to 20" wheels you lose capability, due to the effective gear ratio change.


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## Nathan

I know minimal about transmissions. However, I do know that an engine oil's big heat generation is shearing of the oil in the Bearings. This increases with the speed (well, square of the speed, but you get the point







). IF you engine has piston cooling jets this will also heat the oil, as will turbos but let's neglect those for now (we're talking about a basic small block here







). If someone were running a test and the oil was overtemping, the easiest way to prevent this is to not let the engine rev as high. Typicaly where you get into heat issues on oil is if the engine is running very fast (<5000 rpm) for extended periods of time. Otherwise, oil temp shouldn't be a big issue.

In short, and engine guy would like it to spin at a decent, but not too fast of speed. If it were me, I'd say 1500-4000 rpm. Hey now, what if you could design an engine that had a flat torque curve across that speed range..... The flat curve would be great for towing AND allow you to run a smaller engine for better fuel economy.... Wouldn't that be great?!?!


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## Carey

CamperAndy said:


> Carey, set fuel economy aside. I sent you on that wild goose chase. The issue is towing capability. When comparing the same truck and drive line and you go from 17 to 20" wheels you lose capability, due to the effective gear ratio change.


Andy. Go do some math. The 20 inch wheels come with 33 tall tires and are only spec'd with a 3.92 ratio. The 17 inch wheels come with 31.7 tall tires and are spec'd with the 3.55 ratio unless you special order the 3.92 ratio. Very few private type dodge 1500's are going to be found with the 17/3.92 combo. You will find that the work truck type dodge 1500 are found moreso with the 17/3.92 combo.

In the end the 20 inch wheel with 3.92 ratio has a lower effective ratio which in turn allows a slightly better towing ability.

You have a slight gain of capability with the 20/3.92 combo versus the standard normally issued 17/3.55 combo.

Dodge has made it so one can run the 20/3.92 combo and still be as capable and as effective as the standard issue 17/3.55 combo.

Ive put all the math above. The engine actually spins faster at 60 mph with the 20/3.92 combo by 125 rpms. This makes for a more capable tow vehicle. Same as taking a truck and going from a 3.73 to a 4.11 ratio.

We do not need to change gears to change efective rear gear ratio. This can be simply done with tire selection.

Carey


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## CamperAndy

Colorado~DirtBikers said:


> We do not need to change gears to change efective rear gear ratio. This can be simply done with tire selection.
> 
> Carey


And if they OP wants to gain towing capability he just gets a set of stock 17" rims and he gets a true 3.92 ratio and better towing.


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## Carey

yes or simply put on a shorter tire.

A 275/60/20 tire makes 634 revolutions per mile. If you times this by the gear ratio, 3.92 the driveshaft would spin 2485 times in a mile.

A 265/70/17 tires makes 658 revolutions per mile. If you times this by the gear ratio, 3.55 the driveshaft spins 2335.9 times a mile.

The 20 inch wheels give you a better towing ability since the driveshaft spins faster. This means that a 20 inch spec'd dodge has a lower final gear than the 17 spec'd dodge.

Now if we go to a 17 on a 3.92 ratio. your driveshaft would spin 2579 times in a mile. This would also increase towing capability.

But as you can see its less than 100 revs more per mile going to the 17/3.92 combo.

WHY? The 17 inch wheel uses a 31.7 tire versus the 20 that has a 33 tall tire. There is less difference using a 33 versus a 31.7 tall tire than using the 3.92 versus 3.55 ratio.

It is not going to be worth your time and money to switch your 20 inch wheels back to 17's. Just not enough difference.


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## Carey

Hopefully my other posts make since now. Dodge has speeded up the driveline to counter the weight mass difference of the 20 inch wheels. They done this so one can buy either truck and have the same towing capabilities with either truck.


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## CamperAndy

Carey I have not argued with your numbers but your rotation per mile are wrong for those tire sizes the 20" will be 611 and the 17" will be 638. The rest make sense but that 100rpm difference is big enough of a change that truck will be noticeably stronger off the mark and if you are due for tires you can buy the 17" tires and rims for the price of the 20" tires. Sure is cheaper then new gears in the rear end.


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## Carey

If you want a better towing capability on the cheap, simply go to a 285/55/20 tire.

The weight rating is. 3305 versus the standard issue 2600 for the 275/60/20 tire. These are load range E instead of P.

They spin 643 so your drive shaft would spin 2520 revs per mile. Versus the factory 2485 revs per mile.

The 285/55/20 tire is spec'd for Ford 1 tons. They are a great towing tire!

BUT! The weight differences are 58 lbs with the 285/55/20 versus, 46 lbs on the factory 275/60/20 tire.

So, are you really gaining anything? Your adding 8 lbs of rolling mass per tire to the vehicle. remember, each pound of rotating weight you add, is equivalent to adding 10 lbs of static weight in terms of performance and mileage.

Since your driveshaft would spin faster with the 285's versus the 275's maybe the difference wouldnt be felt.

But oh yes... Huge amounts of engineering is done on a vehicle concerning tire, wheel and gear choices. Hopefully Ive proven that.


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## Carey

My numbers come right from tire rack. You can use this page. http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=LTX+A%2FT+2&partnum=855R0LTXAT2&vehicleSearch=false&fromCompare1=yes just click the specs button below the tire on the page.

The michelins are 630 for the 20's and 657 for the 17's. Michelin tires are always a bit smaller. I used the actual factory specs. Close enough. All 3 tire sizes are here on one page.


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## Carey

Ive seen people say that the 20 inch wheel option takes off 1000lbs of towing ability. Ive seen this for years. I have known this to be BS the whole time. I knew I would have to spend a day to prove that a 20 inch spec'd dodge 1500 is actually a more capable towing vehicle than the standard issue 17/3.55 combo. Today I am stuck waiting for parts. Why not bust this myth today I thought.. Got nothin better to do.

So now Ive done it. On to the next challenge, lol

Not being mean here Andy. Just having fun.

Carey


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## CamperAndy

Well I had not checked tire rack but after looking at several to check for consistency in size relationships I see that they vary widely depending on the tire manufacture. So there is a large amount of variance in tire of the same size. That can explain the errors in speedometers.


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## CamperAndy

Colorado~DirtBikers said:


> Ive seen people say that the 20 inch wheel option takes off 1000lbs of towing ability. Ive seen this for years. I have known this to be BS the whole time. I knew I would have to spend a day to prove that a 20 inch spec'd dodge 1500 is actually a more capable towing vehicle than the standard issue 17/3.55 combo. Today I am stuck waiting for parts. Why not bust this myth today I thought.. Got nothin better to do.
> 
> So now Ive done it. On to the next challenge, lol
> 
> Not being mean here Andy. Just having fun.
> 
> Carey


MY premise was for the same truck a 20" tire is a towing hit as compared to a 17" and you have also proven that. Now you can run the numbers for a 4.10 and a 3.73 rear end and see what tire to get.


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## Carey

Yes sir Andy. There is about a 5 rev difference between all mfr's of tires. If you want an accurate speedo, you need to re-enter revs per mile for each brand of tire you pit on. Then as the tire wears you could change it again by a rev or two.

As a tire gets larger so does the variance.


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## Carey

CamperAndy said:


> Ive seen people say that the 20 inch wheel option takes off 1000lbs of towing ability. Ive seen this for years. I have known this to be BS the whole time. I knew I would have to spend a day to prove that a 20 inch spec'd dodge 1500 is actually a more capable towing vehicle than the standard issue 17/3.55 combo. Today I am stuck waiting for parts. Why not bust this myth today I thought.. Got nothin better to do.
> 
> So now Ive done it. On to the next challenge, lol
> 
> Not being mean here Andy. Just having fun.
> 
> Carey


MY premise was for the same truck a 20" tire is a towing hit as compared to a 17" and you have also proven that. Now you can run the numbers for a 4.10 and a 3.73 rear end and see what tire to get.
[/quote]

Ok I will.. gotta eat supper... You have made me work today, lol Be back after a while with munbers, I mean numbers, lol


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## Nathan

Colorado~DirtBikers said:


> If you want a better towing capability on the cheap, simply go to a 285/55/20 tire.
> 
> ....
> 
> The 285/55/20 tire is spec'd for Ford 1 tons. They are a great towing tire!
> 
> ......


So, wouldn't it be easier to buy a Ford 1 ton and be done with it?!!


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## Dads3girls

Bennitt5 said:


> Just to throw in my 2 cents I would call dodge and give them your vin number and they can tell you exactly what the truck was rated for. I have done this with my 2004 1500 quad cab with the 5.7l hemi. I have hauled my last two campers with the 1500 one was 30ft and the other was 32ft. my last truck could haul them fine but I never missed a gas station. I just upgraded to an 07 with the 6.7L diesel and I would never go back. They are a world apart.


I had the dealer run the VIN and I have the rated towing capacity of the tuck. For the 2007 RAM 1500 Crew Cab 4x4, 5.7L. Hemi, 3.92 rear, the capacity was 9,950# (looking at the paper work now- see attached). Not sure where the dealer got it.


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## Carey

Nathan said:


> If you want a better towing capability on the cheap, simply go to a 285/55/20 tire.
> 
> ....
> 
> The 285/55/20 tire is spec'd for Ford 1 tons. They are a great towing tire!
> 
> ......


So, wouldn't it be easier to buy a Ford 1 ton and be done with it?!!































[/quote]

LoL Mr. Peanut Gallery Nathan!

On the diesel single tires they come with a 245/70/17 E rated tire. They are around 30.5 tall and do 682 revs per mile. Sure would be nice if dodge offered the 20 inch wheel option on the HD trucks.

So a 245/70/17 tire has 682 revs per mile. Driveshaft speed would be 2543 for 3.73 and 2803 for the 4.11. Yep a pretty big difference.

If one was to buy a truck with 4.11 gears and switch to the 285/55/20. The revs per mile are 643. This would put your driveshaft speed at 2642.

If one was to have a 3.73 geared truck and then go to 285/55/20 the driveshaft revs would be 2398 per mile.

Now if we take the driveshaft speed of 2398 per mile, then times that by say .70 which is avg for an overdrive, your rpms would be 1678 at 60 mph. If we take that same tire with its 643 per mile rev and use a 4.11 with a .70 overdrive we'd be at 1962 at 60.

That would be right about where my dually is at. 1960 rpms at 60 mph. I love this gearing for towing, but hate it when empty.

The 3.73 with a 20 tire might have a tranny that gets pretty hot on the 4 speed auto models.

But the new dodge 6 speed does run right in the 1600 range at 60mph. It would not do well at all with the 20 inch tires though.

I have thought hard and long about converting my dually back to a single tire and use bushwacker fender flairs on the rear so I could keep the wider dually axle. But because I weigh 8-9000 fairly often I feel Im stuck with my dually. Sure would be cool to have a 285/55/20 on a nice alcoa rim though. It would still be within about 4 inches on the rear width by using the dually axle. I feel this would give me a good 1mpg boost in mpg. Yes a hybrid dually.

On most cummins trucks we'd like to lower rpms instead raise rpms. But the new 6 speed truck now get the rpms down into a better gear for empty running. The guys who tow heavy, 23-25k lbs say the new 6 speed still hunts around quite a bit.

What is optimum on a HD dodge? Well since most come with a 3.73, Id say nothing larger than something like a 265/70/17 e rated tire. Tire revs would be 657, which would give us a 2450 driveshaft speed per mile, and a 1715 rpm at 60 mph. That would be a perfect tire if one was only towing a max of around 10000 lbs. We would have a 65 rpm difference over factory. Factory was 1780, new tire would be 1715 rpms. You might gain a few tenths of mpgs while towing and I bet would gain .5 mpg empty..

But you would need to keep your tow weight around a max of 10-11k and try and keep total gross to 18k or so.

Remember gearing needs increased as more weight is added. Many of you here are not even close to the max weight specs for your diesels. If one was to optimize tire size to your max weight a gain of fuel mpg could be had both empty or loaded.

One needs to take weight, gearing, tranny gearing, and type of trailer into account here. Dodge has given us the best of all average worlds. On our diesels we have the ability to customize tire sizing to equal our weight to gain fuel mpgs.


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## Carey

My dually has a 3.73 ratio, and a 235/80/17 tire. 31.8 tall It revs 656 per mile. Driveshaft speed is 2447. (3.73 times 656) I have a .79 overdrive so my rpms are at 1933 at 60 mph. I can tell you this is exactly right on. I take 2447 times .79 and this gives me my rpms at 60 mph, 1933 rpms.

Just want you all to know that you can easilly find the actual revs you are going to run when making tire, wheel and rear gearing changes.

Its very simple math once your learn how to do it. You can customize your tire, wheel and gear choices very easy by using this method.

Carey


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## Carey

Dads3girls said:


> Just to throw in my 2 cents I would call dodge and give them your vin number and they can tell you exactly what the truck was rated for. I have done this with my 2004 1500 quad cab with the 5.7l hemi. I have hauled my last two campers with the 1500 one was 30ft and the other was 32ft. my last truck could haul them fine but I never missed a gas station. I just upgraded to an 07 with the 6.7L diesel and I would never go back. They are a world apart.


I had the dealer run the VIN and I have the rated towing capacity of the tuck. For the 2007 RAM 1500 Crew Cab 4x4, 5.7L. Hemi, 3.92 rear, the capacity was 9,950# (looking at the paper work now- see attached). Not sure where the dealer got it.
[/quote]

Sounds correct to me. The dealer has it in there computer data base. Your max combined weight rating should be 15200-15500 lbs. But payload is around 1400. Thats the killer number that hurts.


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## gonewild

Seeing that we're just having fun. Those RPM #'s aren't accurate. They were calculated using a transmission OD ratio of 1:1. Not many trannys are so equipped, most automatics w/OD run approximately a 0.69:1. The RPM's will actually be lower. The percent difference will be the same as what Carey states just the numbers will be a bit off. When in doubt just step up and get a diesel. You will not feel such a minimal difference in effective ratios.


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## Carey

Yeah I know. I was using a 4x4 table for gearing when I wrote that this morn.

After thinking back to my college days I remembered how to do the math correctly. Been a lil while, 25 years, lol

Yep you are right, diesels dont feel gearing and tire changes as easilly.

Carey


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## jhayes

Dads3girls said:


> I just bought a 2007 Dodge Ram 1500 Crew Cab with the 5.7 Hemi and 3.92 gear ratio.
> The dealer info says it has a towing capacity of 9,850 lbs.
> I also just bought a 2007 28RSDS with a dry weight of just over 6,000 lbs.
> I have a WD kit that will be installed with 800 lbs rating on the bars and an friction sway bar.
> This is the first time with a larger truck and larger trailer.
> Can anyone tell me what to expect.


Jeff,

I had a 2004 Dodge Ram 1500 5.7 Hemi (signature below) with the tow package and pulled a Keystone Outback 26RS (5200# shipping weight). The numbers on the truck were similiar to your vehicle. My truck was was fine on flat highway but any type of incline, it did alot of gear searching. The truck was begging me to slow down and give it a break. I finally realized that the truck just wasn't going to handle the task. I upgraded to a 2006 Dodge Ram 3500 diesel and no longer an issue. The truck runs so smooth pulling the trailer, you don't even know your pulling it. I get twice the gas milage with the diesel compared to the gas.

My only suggestion to you try and not come close to GCVWR. A 20% window is a good number to try and not exceed. The longer you have your TT, the more weight you'll gain by adding items you feel you need (generator, grills, lawn chairs & etc).

Good luck and happy camping.


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## ProPerDoper

I signed onto the forum here after reading this entire post with great interest.

I also own a 2006 Dodge Ram 1500 QC 2WD SB 3.92:1 Auto with OEM 20" Wheels. I want with everything I've got to believe that I have a higher tow capacity than what the factory brochure or the Trailer Life Tow Guide says.

For the record, each states a reduction in tow capacity for the 20" wheels, both in 2006 and in more recent editions:

The 2006 TL tow guide states 7650 lbs. capacity. (1500 QC SB 2WD 5.7L V-8 7,650a,d*) 
http://www.trailerlife.com/images/towratings/2006/TowingRatings_p20_33.pdf

The 2006 Dodge sales brochure states 8750 with no mention of the 20" wheel option.

The 2008 TL to guide states 8500, with no mention of the 20" wheel option. (1500 QC Shortbed 4WD 5.7L V-8 8,500 (a,h,t))
http://www.trailerlife.com/images/digitaleditions/pdfs/DigitalTLTowGuide0801.pdf

The 2010 Dodge BodyBuilder guide states 10,200, and specifically calls out the 3.92:1 and 20 inch wheel options:
http://www.dodge.com/bodybuilder/2010/docs/ram/rammlup1500.pdf

I also read recently that Dodge engineers recalculated their tow ratings without any changes in hardware:
http://blogs.insideline.com/straightline/2009/07/revised-2010-dodge-ram-tow-ratings-not-just-advertising-hype.html

So....as bad as I want to believe that my Dodge has a higher tow rating than the earlier published 7650, 8750, or whatever it was, how does one confirm the rating?

BTW...I called Dodge, was given a case #, and advised that I would get a return call only to have a voicemail left on my cell stating the max my truck can tow based on the Vin # provided was 2000 lbs! Sheesh! 
(I have to assume that's because the dealer had to install the receiver hitch, so they may be basing that number on a bumper hitch?)

It's a tough issue to gain clarity on, especially if you'd like to follow some recommendations to stay 20% below GVWR of any trailer towed.


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