Difference Between Bias Ply Tires # AM1ST90 and Radial Ply Tires # AM10234

Question:

i have a ST205/75/14 what is the diffrence in a d14

asked by: Kenny B

Expert Reply:

The difference in tires that have either a D or an R in the tire size description is that a D indicates a bias ply tire, and an R would mean it is a radial ply tire. Examples of each type are ST215/75D14, part # AM1ST90, and ST215/75R14, part # AM10234. The difference in the construction of the tires is that the cords underneath the tread run in different directions. On a bias ply tire, the cords run at a 32 degree angle from the direction of travel. On a radial ply tire, the cords will run at 90 degrees from the direction of travel or across the tire from wheel lip to wheel lip.

A bias tire has a little stiffer sidewall and is commonly used more for off-road applications, like farm use. The radial tire will run cooler and last longer if it is not overloaded.

I have linked you to an FAQ article that addresses questions about tires.

expert reply by: Jeffrey L