When the unthinkable happens on the road, you might need to call the local mobile truck tire repair company. But before you call the mobile truck tire repair company, you will need to know how to identify the size and type of tire on your semi truck. This is the last guide you will need to read to learn how to properly identify truck tires on the fly. One of the most important factors of the semi truck is the tire size – transmission gearing, road speed, and other driving conditions are largely affected by the choice of tire. Combined with the fact that trucks are often carrying tons of (potentially valuable!) goods, this is not a choice that should be taken lightly.
Types of Semi Truck Tires
An example semi truck tire format is as follows: 11R22.5G. The numbers before the first letter corresponds to the section width and aspect ratio of the vehicle – if the numbers have a slash involved (i.e. 295/75R22.5G), the tire is low-profile instead of standard (low profile typically offers less weight and better performance for highway trucks). R corresponds to a radial tire; bias ply tires will have a dash (-) in its place instead. The number after the wheel type is the wheel diameter, and the last letter is the load rating. More details will be explained in the following sections.
Tire Aspect Ratio
Semi truck tire sizes ranging from 8-12 are standard profile tubeless – the body width is listed in inches, and the aspect ratio is 88% (i.e. the length between the rim to tread is 88% of the width). For instance, using the example from above, an 11R22.5 tire will have a height of approximately 9.5 inches and a width of 11.
For low-profile tires, the width is in millimeters instead (the aspect ratio is the number after the slash). For instance, a 275/80R22.5 tire will be 275mm wide and 220 high. Aspect ratios are usually either 70, 75, or 80%. If the tire requires an inner tube, the aspect ratio is 98%.
Wheel size is measured by inches, and corresponds to the diameter of the tire. Sizes that are whole numbers (common: 20, 22, 24) require an inner tube, whereas half-inch tires (common: 19.5, 22.5, 24.5) are tubeless. The wheel size corresponds to the last number 22.5 in the full size of the truck tire 275/80R22.5.
As mentioned above, the last letter in the tire size format is the load rating (i.e. maximum weight capacity of the tire). The popular rating “G” in the examples mentioned above correspond to a 6175lb load capacity while inflated at 105psi, whereas “L” can correspond to over 12000. Please note that the load ratings of dual-mounted tires will be slightly lower, and that load ratings change based on tire pressure – refer to the manufacturer-provided charts for more information.
Mobile Truck Tire Repair
If your semi truck has a tire blow out on the side of the road. You should call a mobile truck tire repair company and read the letters numbers on the exterior side of the truck tire which are formatted like this 275/80R22.5. This is the size of your semi truck tire. They will need these numbers to determine the type and size your semi truck tire.
Plaehn, Tim. “Explanation of Truck’s Tire Size.” It Still Runs, 12 June 2017, itstillruns.com/explanation-trucks-tire-size-6167038.html.