How to Read Your Tire Sidewall: What All Those Numbers and Letters Mean

Every tire has a code stamped on its sidewall that looks something like P215/65R17 98H. To most drivers, it's meaningless. But that string tells you exactly what kind of tire it is, what size it fits, how much load it can carry, and how fast it can safely travel.

The First Letter: Vehicle Type

"P" stands for passenger vehicle. "LT" stands for light truck. If you're replacing tires, match this designation to your vehicle's requirements — mixing P and LT tires affects load ratings and handling.

Section Width

"215" is the tire width in millimeters, measured sidewall to sidewall. A wider number means a wider tire, affecting traction, fuel economy, and wheel well fitment.

Aspect Ratio

"65" is the ratio of sidewall height to section width as a percentage. Lower numbers (40, 45) mean low-profile, stiffer tires. Higher numbers mean taller sidewalls that absorb more road impact.

Rim Diameter

"17" is the wheel diameter in inches. This must match your rim exactly.

Load Index and Speed Rating

"98" is the load index (98 = 1,653 lbs per tire). "H" is the speed rating (H = 130 mph max). Never install a tire with a lower speed rating than your vehicle requires.

DOT Code: Age Matters

A four-digit DOT code (e.g., "2322") means the tire was made in the 23rd week of 2022. Tires degrade with age even without mileage — most experts recommend replacing tires over 6–10 years old regardless of tread.

At Junior's Auto Repair in Twin Falls, we help drivers pick the right tires for their vehicle and budget. Stop by 417 Main Ave E or call (208) 595-2101 — Monday through Saturday, 9 AM to 5 PM.