ST175/80R13 Trailer Tire Recommendation for 2003 Rockwood Premier

Question:

My tire says st175/80r13. Im finding tires that say d13 not r13. Whats the best one

asked by: Angela

Expert Reply:

The difference between the D and the R is that R indicates radial and D indicates bias ply construction.

The main difference between a radial ply and a bias ply tire is how the tire is constructed. The cords inside a bias ply tire run at a 32 degree angle to the direction of travel, and the cords on a radial tire run at a 90 degree angle to the direction of travel, or across the tire from wheel lip to wheel lip.

A radial tire flexes more than a bias tire, giving it better ground contact, traction, stability, and tread wear. A radial tire will normally run cooler than a bias ply tire, especially when the tire is under a load. A tire that runs cooler will last longer.

A bias ply tire has a stiffer sidewall than a radial, a feature that might be useful for off road applications like farm use. At one time radials were more expensive than bias ply tires, but now they are closer in price. This makes radials a much better value.

We have the part # TTWTRTM1758013C which is a ST175/80R13 which is a radial tire and would work well. Unlike most trailer tires this one has an 81-mph speed rating as well.

expert reply by: Jameson C