Tires and what you need to know about them.

Tires. We all know we have to have them. We all hate buying them. Tires are the second largest purchase you will make after buying a new car. So what do we need to do to make them last? The tire size branded on the sidewall provides a significant amount of information about the tire’s intended purpose, dimensions, load capacity and high temperature/high speed durability. Most tire sizes begin with a letter or letters that identify the type of vehicle and/or type of service for which they were designed. Below is some basic info that is on the side of you tires.

Section Width: Following the letter(s) that identify the type of vehicle and/or type of service for which the tire was designed, the three-digit numeric portion identifies the tire’s “Section Width” (cross section) in millimeters.

Sidewall Aspect Ratio: Typically following the three digits identifying the tire’s Section Width in millimeters is a two-digit number that identifies the tire’s profile or aspect ratio.

Internal Construction: A letter (R in this case) that identifies the tire’s internal construction follows the two digits used to identify the aspect ratio.

Speed Rating: Today, the only tires that continue to include the speed rating “in” the tire size (P225/50ZR16) are Z-speed rated tires. In this case, following the two digits used to identify the aspect ratio are the letters ZR to identify the tire’s speed rating (Z) and its internal construction (R). Since 1991, all other speed ratings are identified in the tire’s Service Description 

Tire and Wheel Diameter:


The 16 indicates the tire and wheel diameter designed to be matched together.

Load Range: The letters on the side of the tire indicate the ply of the tire. Your P tires are low load range passenger tires which are 4 ply. The LT on your tire is for larger light duty tires and will be 6, 8, and 10 ply. Most larger AT and MT ( All Terrain and Mud Terrain ) tires are 10 ply. Ply refers to the layers of rubber and nylon applied to strengthen the tire.


Tread Pattern: The tread pattern is important when selecting a set of tires. The grooves in the tires are known as sipes. Tread patch and sipes play a important roll. The sipes filter out water and debris and the tread patch it the amount of rubber that comes in contact with a certain surface.

Author: Shawn Thomas