# Tires



## Lady Di (Oct 28, 2005)

I am researching replacement tires for the OB. Our current tires are Duro bias ply, 4 plies sidewall, 2 plies nylon. First of all, does this mean that the sidewalls are only 4 plies or are they 6 plies total.

Second question is; what are the advantages/disadvantages of bias ply vs radial?

As you can tell, this is one area I don't really know a lot about.

Help!


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## PDX_Doug (Nov 16, 2004)

Lady Di,

If the tire says it has a 4 ply sidewall, then I think you are safe in assuming that it is 4 plies total. If it is stated on the tire, as you did here, that is a little confusing though.

As far as radial vs. bias ply, I did a good bit of research on this when I replaced my tires. The bottom line seems to be, if you are towing primarily on paved roads you are better off with radials. If, on the other hand, you do a lot of back country towing on dirt or gravel roads, the bias ply tires will serve you better.

Happy Trails,
Doug


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## daslobo777 (Mar 24, 2007)

Lady Di -

What you stated means that there are 4 plys throughout the tire (sidewall + treads) plus an additional 2 plys of nylon on the tread area for durability/puncture resistance. If the nylon was in the sidewall, the tire would be too stiff.

What PDX-Doug says on the radial vs bias is right-on, the radial provides a smoother and less rolling resistance on the highway but is less durable in the rough stuff.

Happy Camping!!


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## map guy (Jan 11, 2007)

The only comment would be to focus on the Load Range Letter instead of the Ply Rating. As Ply numbers can be deceiving in relationship to the actual load capacity of the tire.

Years ago the load rating of a tire was based on its amount of Ply's it contained. Today the proper way to judge the tire capacity is to use the Load Range Letter.

Most OB's come from Keystone with Load Range C tires Example from 23RS - ST205/75D14C

ST = Special Trailer 
205/75 = Aspect Ratio Tread width to height ratio
D = Bias Belt Construction (R here would mean Radial Ply construction)
14 = Rim Diameter
C = Federal Load Range (Tire weight capacity)

IMHO cannot go wrong with Maxxis, Goodyear Marathon, Denman, GreenBall brands. Radials do have lower rolling resistance in relationship to bias type tires -just make sure that all four trailer tires are bias or radial -don't mix the two types.

Hope this helps









Map Guy


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## tdvffjohn (Mar 10, 2005)

I was told the radials will run cooler than bias ply so I put radials on mine in anticipation of a lot of miles on the west coast this summer.


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## Lady Di (Oct 28, 2005)

Thanks, Sounds like we have a radial upgrade in our future. At this time we are not planning on upgrading to 15". Sure wish we could though.


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## NJMikeC (Mar 29, 2006)

Maxxis will ship tires to your door for likely just a tad above what you can buy Goodyear Marathons for. I have heard good but more bad about Marathons so I elected to be a guinea pig of sorts and go with Maxxis.


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## outbackgeorgia (Jan 28, 2004)

I have had Maxxis radials for over a year.
Great tires.
Radials have less rolling resistance, therefore less heat.
They are great, I moved them to the 25RS-S from the 21RS.

Dave


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## redmonaz (Jul 24, 2006)

I put GoodYear radial marathons on our 26RS a few monthes back. I had always heard you should use bias on a trailer, but all the new info says radials are better. We only had it for one trip about 300 miles total. They seemed to track better and worked fine so far.

The price of a radial over a bias was not much. I got all 4 at discount tires for $396 out the door. Some people have done better than that.

Good Luck,
Don


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## MJRey (Jan 21, 2005)

I've got the Maxxis radials and they seem to be doing well. I've got about 2,000 miles on them so far. You can get a little bit more capacity if you go with the 215/75-14 instead of the 205s that a lot of the trailers came with.


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## Lady Di (Oct 28, 2005)

Mark,

Do the 215's fit the 205 wheels?


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## PDX_Doug (Nov 16, 2004)

Lady Di said:


> Mark,
> 
> Do the 215's fit the 205 wheels?


Most wheels are capable of fitting a limited range of tread widths. The difference in width between a 205 and a 215 is only about 5/8", and you should be fine. Your dealer can verify that when he sees your wheels (or, if you can give him the wheel width).

Happy Trails,
Doug


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## Lady Di (Oct 28, 2005)

Thank you Doug,

As I said in the first post, 'I am somewhat tire size' illiterate.

Just one more question, when upgrading to 15" tires, what is the load rating on the axles? Can they handle the increased losd if there is one?


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## map guy (Jan 11, 2007)

Lady Di said:


> Thank you Doug,
> 
> As I said in the first post, 'I am somewhat tire size' illiterate.
> 
> Just one more question, when upgrading to 15" tires, what is the load rating on the axles? Can they handle the increased losd if there is one?


Generally speaking load rating on the axles will not change with just a tire and or rim upgrade. Increasing axle capacity is a little more involved but not by any means rocket science. Depending on what brand/model axle your trailer currently has will determine how easy/hard and costly it would be to increase this capacity. On some OB's a simple change out of the leaf springs will increase axle capacity enough to require 15" tires and rims. Other model OB's will require new axles and springs to increase this capacity.

Are you trying to increase your trailers carrying capacity or are you trying to increase its' margin of safety during towing? Safety margin is improved by the change from 205 to 215 size tire staying with the 14" tire. Changing to the 15" tire /rim does the same thing unless suspension capacity is increased proportionately, too.

Think of the statement " The chain is only as strong as the weakest link" - the relationship is that your trailer carrying capacity is determined by the weakest/lowest weight capacity component. From the factory most OB's models are limited by the tire capacity first then by suspension component capacity second.

Hope this wasn't to convoluted for you to understand.

Map Guy


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## Lady Di (Oct 28, 2005)

By SOME miracle I did unterstand. Thanks!


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