How Are Truck Tires Measured?

Determining the Service Type

Tires that are designed for trucks are marked with an "LT" in front of the measurement for "Light Truck." They include SUVs, box trucks and trucks that haul equipment and other items.

Section Width

The first three-digit part of the measurement is the section width. This means the area that you would see between your fingers if you spread your hand across the tread of the tire, the surface that will touch the road. But it also includes down the sidewall to the widest point.

Sidewall Ratio/ Inner Construction

The next number, which is a two-digit number, is the sidewall aspect ratio, which is generally the tire's height from rim to tread. This is also known as the profile number. For example, on a sports car, you may have thinner tires, which are called low-profile. For a truck, you want a taller sidewall ratio.
Immediately after this number, you will see a letter; this is the inner construction and is usually an "R" for "radial."

Tire and Wheel Diameter

The next number in the series is the size of the wheel that the tire will fit. This is one of the most important measurements to check before mounting a tire on the rim.

Sample Tire Measurement

For example, a truck tire measurement of LT225/65/16 means that it is a light truck tire with a width of 225, height of 65 and wheel size of 16. The measurement is printed on the sidewall of the tire for quick reference.