Thursday, December 1, 2022


RV Tire Safety: What’s the best tire for my trailer?


By Roger Marble
“What’s the best tire for my trailer?” We have all probably seen this question on an RV forum or two. The problem is that many people have their personal choice, but I doubt that any person has ever done any extensive controlled testing. If you think about it, why would anyone have a favorite brand but would be running a different brand unless forced?

As a tire design engineer, I always depend on facts and data, and try and stay away from just an opinion. However, since there is no way I can do a comparison of dozens of different brands in dozens of different sizes, sometimes I do have to fall back on “opinion.” But if we think about tire performance and durability in general, I think we can come up with some information that can guide us to a shorter list of potential choices.

All tires have a “Material List” molded on the sidewall. Based on this information plus a few generalities, I think we can develop a plan.

Looking at your current tires, you will see what materials are in them. I suggest you write the information down so you can keep the information organized.

Let’s talk about tire construction

Modern ST-type radials will usually have one or possibly two ply or layers (we can use the terms interchangeably) in the sidewall. The material used is usually polyester. They will also have two ply of steel belts in the tread. Now, this is the important detail. Some tires may also have one or two ply of nylon or some other material in the tread in addition to the two ply of steel. This is the important part.

Radial tires have a high stress location at the edges of the belt. I have a number of posts on my RVTireSafety blog (and on that focus on this force (Interply Shear) and location. Here is the most important one.

One way that tire companies can address the Interply Shear and end up with a tire that might perform better on the special tests like High Speed that tires need to tolerate if they are going to have a higher “Speed Symbol” marking is to add a ply of nylon on top of the steel belts.

Not all tire companies report the tire materials in advertising

The problem you as a consumer face, is that not all tire companies report the materials in their advertising. But the good news is that the information molded on the tire sidewall must, by law, be accurate. So if the tire says it has nylon ply, it must have the nylon. Now, a performance improvement is not guaranteed. But, in general, it is likely that tires with nylon ply above the steel belt edges can have lower Interply Shear forces. They should perform better and possibly last longer.

So, lacking any other data, I would use the nylon as a plus for a tire if I were considering two different brand tires.

You may need to talk with a tire dealer and possibly need to confirm yourself what the material list on a tire actually says.

Bottom line

You can confirm which ST-type tire you are considering has the nylon cap ply and which does not. If they are different, then it is possible that the tire with the nylon might be a better choice. Please remember that this is not an absolute, as without actual performance data we cannot be certain of the future performance. But this is something we can consider, and this data is better than just a wild guess.

Have a tire question? Ask Roger on his new RV Tires Forum here. It’s hosted by and moderated by Roger. He’ll be happy to help you.

Read more from Roger Marble on his blog at or on


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10 months ago

I, and others I know, have gone to the Goodyear Endurance for our big 5th wheel RVs and have been quite happy with them.

Roger Marble
10 months ago
Reply to  Impavid

And to help others, What does the sidewall say your construction materials are?

10 months ago
Reply to  Roger Marble

Taken from the internet, the Endurance are described as: The tire features an internal structure that includes twin steel belts with a two ply nylon reinforcement to stabilize the tread, increasing traction and durability. The Endurance also features a polyester cord body to help smooth out the trailers ride, and a scuff guard is molded into the sidewall to further increase durability by resisting damage from contact with curbs during parking lot maneuvers.

Roger Marble
10 months ago
Reply to  Impavid

Thanks, Your information means your tires say something like this… “Sidewall, one layer Polyester. Tread, 1 layer Polyester + 2 layer steel + 2 layer Nylon”. People need to remember that the number of layers of Nylon might change if you change the tire size so everyone needs to check their own tires.

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