# Towing And Tire Size



## Stacey (Apr 25, 2004)

We currently have a 2001 Suburban with the 5.3 v8. It really struggles on the hills and one thing that we were considering was replacing the existing tires which are 265/70R16 with 245/70R16. Since the radius of the tires would be about an inch less, the change in tire size would accomplish the same thing as increasing our rear differential. The question is, can we tow with the lower load capacity of the smaller tire. The larger tire has a load capacity of 2400 lbs per tire at 35 psi (the reccommended tire pressure on the door) and the smaller tire would have a load capacity of 2000 lbs per tire at 35 psi.

The question is can we get away with the smaller tire. I'm concerned about the reduced load capacity of the tire at 35 psi. One option would be to buy a tire that is rated at a higher psi, which in turn would provide a load capacity equal to or greater than the old tire, however the suburban owner's manual states that maximum tire pressure should be 35 lbs. Any comments??


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## CamperAndy (Aug 26, 2004)

The tire pressure rating is based on the stock tires. If you upgrade the rating or change from P to LT tires you can go up to the max tire pressure listed on the tire. This will effect ride comfort but many people max out the tire pressure when towing and then bleed it down when not.


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## Jay (Apr 24, 2005)

You need my spare TV....I bought an '05 2500HD Chevy Sub, LT, 8.1v8, 4x4 to handle the 30RLS Outback the DW wanted. THEN...I traded a 2002 F150 for an 05 Chevy 3500 LT, DW, 4x4 in June to get ready for the 5'er my DW now wants. The Suburban was a mistake at the time (didn't anticipate the 5th weel).

Now I have a spare TV......this baby will snatch a building up a freeway ramp in a heartbeat. (05 Sub).

I feel stupid, but DW loves her personal SUV. Let me know if you want to buy the Suburban...I'll make you a good deal.

Jay
[email protected]


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## huntr70 (Jul 8, 2005)

I would personally make the switch, but I would go for an E range LT tire, as CamperAndy suggested. It will also help with sway control, as the LT E range have a much stiffer sidewall.

I have the 265/70R16 on my Dodge in LT E range and it really doesn't make that much of a difference in ride quality if you air up when towing and bleed out again when done.

Just expect to more per tire when going to LT E range tires.

Steve

Just thought of this...the Chevy 2500 pickups run 245 series LT tires.


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## Fire44 (Mar 6, 2005)

I have a 2000 Suburban 1500 with the Firestone Wilderness LE in P265/70R16 and pull my 27RSDS. Chevrolet's manual states 35 psi for the tires but when I am going to be pulling my trailer I increase the pressure to 44 psi (the max that is on the sidewall for the tire). Chevrolet's pressure is what is required to carry the weight of the Suburban and a full load of people, to get to the max capacity of the tire you have to look at the sidewall on the tire.

That being said when these tires are done they will be replaced with LT265/70R16 load range E for the same reasons stated above.

I don't know if dropping to 245/70R16 would change the towing ablity that much, it will change the speedometer but not by much.

Gary


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## JimWilson (Feb 24, 2004)

You would be changing the effective gearing by such a small amount that, personally, I don't think it would be worth the time, money or effort (I say "effective" because in reality you aren't changing the actual gearing).

If you have 3.73's in your truck now the tire change would net you about the equivalent of 3.92's. That's hardly worth it, and wouldn't really be all that noticeable. You'd be stuck looking at a truck with puny tires, and you really wouldn't have gained all that much.

If you want to spend that type of money you might want to check into some of those PCM retuners from the likes of HyperTech, SuperChips, Predator, etc. They may be able to eek out some additional performance from your truck, which in turn would make your towing a bit better. They all have money back guarantees, so you can actually give it a try and see if it would be worth it to you.


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## CamperAndy (Aug 26, 2004)

JimWilson said:


> You would be changing the effective gearing by such a small amount that, personally, I don't think it would be worth the time, money or effort (I say "effective" because in reality you aren't changing the actual gearing).
> 
> If you have 3.73's in your truck now the tire change would net you about the equivalent of 3.92's. That's hardly worth it, and wouldn't really be all that noticeable. You'd be stuck looking at a truck with puny tires, and you really wouldn't have gained all that much.
> 
> ...


On the new Dodge Rams there are 20" tire options (17" stock) the tire sizes are really not that much different as the side walls are taller on the 17" tires but there is still a difference. The 20" tires results in 1000 pound towing penalty no matter what the rear end gear is.


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## huntr70 (Jul 8, 2005)

CamperAndy said:


> JimWilson said:
> 
> 
> > You would be changing the effective gearing by such a small amount that, personally, I don't think it would be worth the time, money or effort (I say "effective" because in reality you aren't changing the actual gearing).
> ...


That is not really a 20" tire option...it is a wheel option...the tire is actually the exact same outside circumference as the 17" wheel. The loss of the 1000 lbs towing is because the wheel is not as structurally sound as the 17"...not as much metal= not as much weight holding capabilities.

...this according the Sales Manager of my local Dodge Boys......









Steve


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## CamperAndy (Aug 26, 2004)

huntr70 said:


> That is not really a 20" tire option...it is a wheel option...the tire is actually the exact same outside circumference as the 17" wheel. The loss of the 1000 lbs towing is because the wheel is not as structurally sound as the 17"...not as much metal= not as much weight holding capabilities.
> 
> ...this according the Sales Manager of my local Dodge Boys......
> 
> ...


Research is the answer. There are 2 basic tire size options for the Dodge ram and I will put the numbers out.

P265/70R17 with a 31.6" OD 99.274 circumference load rated at 2535 pounds
P275/60R20 with a 33.0" OD 103.672 circumference load rated at 2601 pounds

Without knowing the towing penalty posted by Dodge you would look at the load ratings of these tires and say they both are more or less the same. The rims must be equal to or greater then the task of supporting the tires load rating. The circumference is the cause of the change in rating as it changes the effective gearing. There could be a discussion about torque rating of the wheels but if I twist a 20" wheel spoke before it breaks a ring gear or drive shaft U joint I would be shocked.

Car salesmen are a bit like RV dealers. You have to really take most of what they say with a grain of salt and my mother always told me to limit my salt!!


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## JimWilson (Feb 24, 2004)

huntr70 said:


> ...this according the Sales Manager of my local Dodge Boys......


And he's right; the rim is the limiting factor.


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## BigBadBrain (Aug 26, 2004)

Jim,
Does that mean that between the rim and the tire it is the rim that is the limiting factor or is he talking about the entire drive train? I'm a little confused by the path of the thread.
Brian


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## CamperAndy (Aug 26, 2004)

JimWilson said:


> huntr70 said:
> 
> 
> > ...this according the Sales Manager of my local Dodge Boys......
> ...


Based on ?


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## JimWilson (Feb 24, 2004)

CamperAndy said:


> Car salesmen are a bit like RV dealers. You have to really take most of what they say with a grain of salt and my mother always told me to limit my salt!!


Be careful of categorizing entire groups of people with such a broad stroke. While I do admit that a disproportionate percentage of the people who sell RV's are either not terribly honest or knowledgeable of their products, not all of us are vermin. Trust me.


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## CamperAndy (Aug 26, 2004)

JimWilson said:


> CamperAndy said:
> 
> 
> > Car salesmen are a bit like RV dealers. You have to really take most of what they say with a grain of salt and my mother always told me to limit my salt!!
> ...


No vermin intent. Sales tactics including lines like, "Sure you can tow this trailer with that truck" or "What do you want to pay per month? I am sure we can work a deal around that". Everyone has a job to do but historically sales jobs where the salesman is trying to make the sale instead of the product making the sale for itself, then there is a grey area there that ends up causing post purchase remorse and a dis like in general for the entire profession. This can not be the first time you have heard this type of generalization but I am sorry if it has offended you. The whistling icon was there to show it was made on the light hearted side.


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## huntr70 (Jul 8, 2005)

I really don't know if I would even want a 20" wheel...besides the rougher ride because the sidewall has less flex.....it would put me into the "dub" category, and I don't know any Rap songs!!!!!





































Steve


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## California Jim (Dec 11, 2003)

Well then just call me "Rappa Jim" rolling on the dubs.


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## tdvffjohn (Mar 10, 2005)

Looks good Jim....................Spinners??

John


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## California Jim (Dec 11, 2003)

Just plain old dubs. Don't even get a second look here in L.A. Gotta be rollin 23's or better, and yes - spinning too


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## huntr70 (Jul 8, 2005)

Rappa Jim......

Looks good. I definitely like the look of after market rims. I just don't think the Factory 20's are that good looking!!!
















Steve


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## CamperAndy (Aug 26, 2004)

Not too much Bling but not bad.


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## California Jim (Dec 11, 2003)

I've always liked the Dodge factory 20's. That's also why I chose the design I did. I like the fairly simple and smooth spokes. Nothing too detailed and also easier to clean. Also, my burb looked like it was on roller skates sitting on the factory 15" wheels!


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## JimWilson (Feb 24, 2004)

BigBadBrain said:


> Does that mean that between the rim and the tire it is the rim that is the limiting factor or is he talking about the entire drive train? I'm a little confused by the path of the thread.


Generally speaking, the entire drive train remains the same (engine, tranny, axles, gearing, etc), so the limiting factor is the tire/rim combo. Now, there aren't many (any?) tires that fit 20" rims which meet LT specs and ratings, but in every instance I've run up against -- I sell RV's for a living, so it's not something foreign to me -- it's been strictly the rims that caused the lower limits.


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## JimWilson (Feb 24, 2004)

CamperAndy said:


> Based on ?


Mostly experience, and conversations with Ford and Dodge.

I sell RV's and have run up against this on more then one occasion. In every instance the limiting factor has been the rims. A fat, wide tire would lower the towing capacity too, but since they actually have higher ratings then the rims -- and you always use the weakest link as the deciding factor -- it's the rims that can be implicated.

Harley edition Fords are a prime example. That driveline is the same as trucks that have 8000+ towing capacities, but those trucks can only tow about 4500. Why? The rims. And that's information directly from Ford.


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## JimWilson (Feb 24, 2004)

CamperAndy said:


> No vermin intent. Sales tactics including lines like, "Sure you can tow this trailer with that truck" or "What do you want to pay per month? I am sure we can work a deal around that". Everyone has a job to do but historically sales jobs where the salesman is trying to make the sale instead of the product making the sale for itself, then there is a grey area there that ends up causing post purchase remorse and a dis like in general for the entire profession. This can not be the first time you have heard this type of generalization but I am sorry if it has offended you. The whistling icon was there to show it was made on the light hearted side.


Everyones job comes with a morals position; anyone, doing anything, can be dishonest at some point. Commission or not. I'm the first to admit that there are too many in this business who are integrity-challenged. I get a bit upset when it seems we're all be categorized like that. Some of us work VERY hard to dispel that image. I go home every night with a clear conscience.

And the "What do you want to pay per month?" question is a very valid one! Most people focus in on a price range, but have no clue what there monthly payments would be. Unlike a car or truck RV loans go on for years; 10, 12 even 15. That being the case, the monthly payments are actually much lower then most people expect (considering they're basing it upon the typical 5-6 year auto loan). If you only look at the sticker price you may end up in something you don't want because you cut yourself off from looking at things that you thought were too expensive. Ultimately, the bottom line is what you have to pay out every month, so wanting to know if someone has established there budget is legitimate.


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## Fire44 (Mar 6, 2005)

I have not said anything, nor have I been offended by anything that has been posted, but as a professional salesperson (20 years in the automotive business) some of the sales tactics are used for a reason. The person that is in looking at a $50,000 Suburban that wants a $250 payment with no money down, we all know that is not going to happen. As for the question "can I tow ______with this truck?", I have to refer to what the truck manufacter saids it can tow, if I tell you anything else then I can be held liable.

We can let the product sell itself, and most will, with the proper demostration. Would you go and buy a new truck, camper, boat, or anything without seeing it??? The salesperson is there to help explain to you the features and benefits of the equipment on the item. And you would have to be ready to pay MSRP for the vehicle (when was the last time you did that?) I would love to go and buy a television, computer, or a pair of shoes and be able to make the kinds of offers that we get in the automobile business.

Just remember there are good, honorable salespeople that will help you select a vehicle that will suit your needs and do the job you need it to do. And there are doctors that will overcharge you for a operation that you don't need, but everyone thinks that the salesperson is the one that is out to get you.

Just food for thought.

Gary
now stepping down off the soap box.


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## btk (Jul 28, 2005)

Gary. Makes me wish I had come to see you when I got my Avalanche last year. No real complaints about Townsend Bros., but a freindly face would have been nice. I'll know for next time. Anyway, back to tire size, don't the 3/4 ton trucks come with smaller 245 series tires that have an "e" rating? Seems they wouold give you a SLIGHTLY better final gear ratio and a heavier load rating.
Brent


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## Fire44 (Mar 6, 2005)

Going from a 265 to a 245 will give you a slight towing advange, but very slight. A tire has a RPM (Rev per mile), the bigger a tire the less turns it makes in a mile (it turns slower). The difference between 265 and 245 would be about 3 RPM....not much of a difference.

I don't know why GM will not put LT265 tires on the 2500HD trucks they put them on the 3500's with single rear wheels. I know that I and other salespeople have asked for the 265 or even 285 tires on the 2500HD trucks but they haven't done it. (I have also suggest a 2500HD with 3.73 ratio with the 6.0 liter, not everybody needs 4.10 ratios but they don't offer them).

Brent, if you are ever in the Smyrna area stop in at Willis and say hi, I might be able to hook you up with a free cup of coffee. (no promises on how good it is)
















Gary


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## johnp (Mar 15, 2004)

I had to ditch my 245's they looked like 4 doughnut spares on my Avalanche. I went with 285's yeh it knock my 3.73 gears down but with the power of that 8.1 who cares. If I choose I can tow at 72 and turn 2100 rpms all day long.

John


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## CamperAndy (Aug 26, 2004)

JimWilson said:


> BigBadBrain said:
> 
> 
> > Does that mean that between the rim and the tire it is the rim that is the limiting factor or is he talking about the entire drive train? I'm a little confused by the path of the thread.
> ...


Jim I guess we will just have to agree that we disagree on this.

The stock Dodge tire choices 17" or 20" result in a 27 rev per mile difference (as the RPM difference was a mentioned issue in this thread), or over 4% difference. This almost exactly equals the difference in a 3.92 gear to a 3.73 gear. This gear ratio difference equals a 500 pound towing penalty.

The P rated 20" tires could have some impact but the towing guides do not mention this as a limiting factor just the rim size. Based on your experience then if I had 20" steel wheels and LT tires I would get that 1000 pounds back but that is not a true statement either as I still have the effective gear ratio effect.


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## mjwencl (Feb 25, 2004)

Caution: Changing tire sizes will change effective gear ratio and will change Towing Capacity.

My rearend ratio is 3.73 and I have the OEM stock LT245/75 R 16E tires.

My effective rearend ratio with changing tires to LT265/75 R 16E's would be 3.59
This would reduce my towing weight capacity also by approx 225 kg - 275 kg (496 - 606 pounds).

As far as gearing goes, if you have a 3.73 rearend and 245/75 R 16 tires (30 x 9.65 x 16), changing to 265/75 R 16's (32 x 10.43 x 16's) would be the same as if you kept your current wheels and tires but changed your rearend gears to 3.59's

When actual vehicle speed is 60 mph (96.54 kph) the Speedometer reading will be 57.76 mph (92.94 kph). A difference of -2.24 mph (-3.60 kph).

Engine RPM with 245/75 R 16's is 1800 @ 55 mph (88.52 kph) Based on 411 tire revs per km (662 revs per mile).

Engine RPM with 265/75 R 16's is 1732 @ 55 mph (88.52 kph) Based on 396 tire revs per km (637 revs per mile).

Replacing your 245/75 R 16 (30 x 9.65 x 16) tires with 265/75 R 16's (32 x 10.43 x 16's) would lower your finish line RPM by 68 RPMs.

Actual tire manufacturers spec vary somewhat from true tire specifications but for this example are sufficient to make this point clearer.

I'll stick with my stock size tire and load rating on my 2500 Crew Cab as it also gets me better winter traction than a wider tire.

Hope this helps some of you making tire decisions.


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## Stacey (Apr 25, 2004)

We just solved our tire problem. We bought a Nissan Titan with the big tow package.


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