How to Measure Truck Tires

Whether a truck's engine is modified or stock, the power produced by the engine must go through the tires before it can be transferred to the ground. Wider tires are more effective at transferring this power and in increasing a tire's ability to grip the road surface, but result in a loss of fuel mileage. Tires which are too wide can extend outside of the wheel wells, necessitating the installation of mud flaps, but can also rub against the wheel well when the tires are turned.
For these reasons, properly measuring truck tires is of critical importance. Note that with the exception of rim diameter, almost all measurements for truck tires are calculated in millimeters rather than inches.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Measuring device capable of reading in inches and millimeters.

1. Measure the overall width of the tire. The overall width is the distance between the outside of one sidewall (the side of the tire) to the outside of the opposing side wall. This measurement includes any decorations on the side of the tire, such as the tire manufacture's label. To properly take this measurement, the tire must be properly inflated and mounted onto the truck.

2. Measure the section width of the tire. The section width of the tire is the overall width of the tire, less any decorations on the side of the tire.

3. Measure the tread width. The tread width is the distance from the inner edge of the tread to the outer edge of the tread.

4. Measure the overall diameter of the tire. The overall diameter is the distance between the top of the tread on one side of the tire to the top of the tread on the opposite side of the tire.

5. Measure the section height of the tire. The section height is the vertical distance from the top of the tread to the bead seat. The bead seat is the inner portion of the tire which rests against the wheel. To properly take this measurement, the tire must be mounted on the wheel, and there must be no load on the tire.

6. Measure the rim diameter. The rim diameter is the distance between the bead seats on opposite sides of the tire. Rim diameter is measured in inches rather than millimeters.