Replacement Tires for Trailer with Size 255/75-15 Passenger Tires

Question:

I have a utility trailer with car tires on it. Can I replace the 255 75 R15s with 205 75 D or R 15s ? If so, should I use D or R ? Thanks

asked by: Grant

Expert Reply:

You are on the right track getting rid of the car tires for trailer tires. Car tires aren't designed for the vertical load that trailer tires are and are more designed for vehicles with a steering axle. The closest tire size we have to what you currently have is 225/75-15 like the part # TTWTRTM2257515D which would be a great option.

The difference between the D and R in the tire size is the construction of it. D means bias-ply and R means radial which is the preferred 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.

expert reply by: Jameson C