How to Read Your Commercial Tire’s Sidewalls

The numbers and letters on the side of your commercial tires provide you with the information necessary to select the right model for your job application.

Tire Width and Aspect Ratio

The first set of three numbers indicates the width of your tire from sidewall to sidewall. There is a forward slash that separates the tire width from a two-digit number for the aspect ratio.

That number represents the percentage of the tire width taken up by the sidewall, or the height of the tire. For example, if the sidewall code is C255/35, multiply 255 (tire width) by 0.35 (aspect ratio) to get the tire height of 89.25 millimeters.

Tire Construction

Tire construction is represented by a letter after the aspect ratio. “R” indicates radial tires with steel belts that run perpendicular to the sidewall. “B” or “X” is for bias ply tires with steel belts laid diagonally from sidewall to sidewall.

Radial tires provide a smoother ride and increased fuel economy on long-haul drives, while bias tires are suited for ag and industrial applications.

Diameter Numbers

The last two or three digits in the first group of numbers and letters on the sidewall are the rim diameter in inches.

Service Description

This group of digits is separate from the tire width, aspect ratio, construction and diameter numbers and letters.

The service description includes:

Load rating: That number is the maximum load that can be carried at a specific inflation.

Speed rating: The letter expresses the maximum speed at which a tire can operate safely. For example, a speed rating of “L” indicates a maximum speed of 75 MPH, while a tire with a “V” rating can reach a maximum speed of 149 MPH.

Department of Transportation Identification Number

The DOT code is a series of numbers and letters that indicate a tire has passed all the safety standards set forth by the Department of Transportation. The three groups of code represent the tire manufacturer’s identification number, tire production location and the date of manufacture.

Buy Commercial Tires at Bauer Built Tire & Service

Bauer Built offers top-rated commercial tire brands. Visit one of our tire service centers around the Midwest and our expert sales professionals will help you find the tire to suit your job application.

Categories: Bauer Built Blog