What Are Differences Between Bias (D) And Radial (R) Tires

Question:

I have 155/80D13 tires. What is the difference in a D tire and an R tire?

asked by: Chuck C

Helpful Expert Reply:

The main difference between a "D" (bias) tire and an "R" (radial tire) is how they are constructed. The cords inside a bias ply tire run at a 32 degree angle to the direction of travel whereas the cords on a radial tire run at a 90 degree angle to the direction of travel. A bias tire has stiffer sidewalls and is generally better suited for off road applications like farm use. A radial flexes more and generally has better ground contact, traction, and stability than a bias. A radial also runs cooler than a bias so normally lasts longer. Bias tires are less expensive than radials but they are now closer in price which make the radial a better value if they suit your situation.

Whatever kind of tire you use, whether a bias tire like the Loadstar Item # AM1ST77 or a radial tire like the Karrier Item # AM10210, it is important to inflate the tire to the maximum psi indicated on the tire and not exceed the tire's maximum rated speed. For example, both of these tires should be inflated to 65 psi.

I have attached FAQ articles on tires and wheels that you may find helpful.

expert reply by: Brint H