The numbers you want to look at will be something like P215/65R17 95T which means nothing until you understand that each number and letter represents a specific measurement. The first number tells the tire type. In our example, P means P-Metric which is for a US passenger vehicle. No letter at the start means it’s Euro metric and has different load capacities. LT at the beginning or the end means it’s for light trucks and probably inflates to a higher pressure.
Next up is tire width from sidewall to sidewall measured in millimeters followed by the aspect ratio after the slash. This measures the ratio of the height of the tire’s cross-section to its width. Our example tires’s height is equal to 65% of its width. A bigger aspect ratio means a bigger sidewall.
The letter R stands for Radial which indicates the layers run radially across the tire and the 17 means that the wheel diameter is 17 inches. The last number/letter combination tells you the tire has a load rating of 95 (1,521 pounds) and a speed rating of T (118 mph.)
Armed with this information, you can hopefully now pick out a set of tires that are right for you!