Tire Research ?

Originally Posted by flyguy

As a side note, when I received the new tires I compared the weight of them with the Goodyear tires, the Trail America tires weighed about twice that of the Goodyear tires, so how is it that both of them carry a load range D rating? Both have stamped into the side info that says two steel belts, 8ply with two plys on the sidewalls. Why do the Goodyear tires weigh a lot less? How much less am I getting for my money with the Goodyear Marathons?

Welcome to the forums Flyguy. Let me see if I can put this simply. A ply rating is just that, a rating. It means that the plies in the tire are equivalent to a certain benchmark. (I think this benchmark was the old original bias tires, but don't quote me on that) An 8 ply/LOAD Range D RATED tire may only have 2 ACTUAL plies in it. These 2 plies are rated to have the same load characteristics as 8 plies of the benchmark standard.

Manufacturers use different materials to make up these plies. Rayon, polyester, fiberglass, cotton, etc. They are even using Kevlar (the stuff in bulletproof jackets) now. Certain manufacturers may use a lighter (but stronger) material than others, which helps account for some the weight differences between brands.

The same holds true for the quality and weight of the steel, they use for the beads and steel belts in the tread. Some may use a thicker steel, but it's not necessarily a stronger steel, but weighs more.

Quality and characteristics of the rubber compounds used, also vary in quality and weight between manufacturers.

So you may read that 2 competing tires have the same rating, and even the same actual number of plies internally, but one brand may use lighter, stronger materials in it's composition, while the other used heavier materials. That's why tires have their ply RATING stamped on them, because the average consumer (or tire salesman) has no idea about what internally comprises their tires......nor would most care. They just need to know the rating in order to make sure it is manufactured to handle the load the tire will carry.

Just because a tire is lighter, doesn't make it a weaker tire.....and the opposite holds true also. A heavier tire isn't always necessarily a better tire.

Have I thoroughly confused you now.

Well WMTire, I appreciate the technical explanation, but the fact still remains, I have had a near miss with the Marathon tires and I can never trust them again, but that is just me, remember that I am charged with protecting the lifes of my family when we travel so I don't take mishaps lightly. Since I work for the U.S. Army here at Ft. Rucker, Alabama, I am familiar with Kevlar because we use it in our helmuts and if I knew for sure that Goodyear was using it to construct the tires I could accept that. As it is, we will just have to wait and see what kind of history the new tires give me. I can tell you that when I left the dealership the tire pressure was 65lbs as trailmanor wants it to be and that at no time did I exceed 65mph and most of the time I was between 55 and 60. I don't think that anyone wants to throw stones, all we want is a tire that we can safely rely on given proper speed and inflation pressure.