Street tire measurements:

Street tires are commonly measured in millimeters by Width / Aspect Ratio x Rim Diameter (inches).


This number represents the load carrying maximum capacity at maximum pressure. See chart below for load ratings conversions See load rating chart


This letter represents the maximum speed under recommended load capacity See chart below for speed ratings conversions See speed rating chart

Aspect Ratio:

The aspect ratio is the height of the sidewall in relation to the width of the tread. For example, if you have a tire that is 160/60R-17, the aspect ratio is 60% of the tread width (the first number in the tire size)

Bias-ply tires:

The carcass of a bias-ply is made of layers of fabric such as nylon or polyester, wrapped over each other in a criss cross pattern. The multiple layers’ flex and create a cushioning effect, which makes bias-ply tires comfortable to ride on and good at handling heavy loads. On the down side, they have more rolling resistance, less control at high speeds, and retain more heat.

Radial tires:

The carcass is made of stiff cords that go straight across the tread, running perpendicularly from one bead to the other, with belts of steel, polyester, or aramid fibers (like Kevlar) criss crossing atop them. Radials tend to be stiffer, allowing better high speed performance, longer tread life, and more precise handling, but the down side is usually a stiffer ride


The charts and information on this page is general information to help you understand the working parts of a tire. Always consult your owner’s manual to determine correct replacements and compatibility. Incorrect selection can result in serious injury or death.