The string of characters on a tire’s sidewall, like P215/65R16 95H, encodes everything about the tire’s size and capability. Once you know how to read it, you can match replacements correctly and understand how a different size would change your car.
What each part means
| Part | Meaning |
|---|---|
| P | Type — “P” passenger, “LT” light truck |
| 215 | Section width in millimeters |
| 65 | Aspect ratio — sidewall height is 65% of the width |
| R | Radial construction |
| 16 | Wheel diameter in inches |
| 95 | Load index (max weight capacity) |
| H | Speed rating |
So a P215/65R16 is a passenger radial tire, 215 mm wide, with a sidewall 65% of that width tall, built to fit a 16-inch wheel. A lower aspect ratio (say 45) means a shorter, stiffer, sportier sidewall; a higher one (say 70) means a taller, more cushioned ride.
Why it matters when you replace tires
Replacement tires should keep the original overall diameter so the speedometer reads correctly and the tires still clear the fenders and suspension. The load index and speed rating should meet or exceed the originals — especially important on trucks that carry weight and on performance cars driven at speed. “Plus-sizing” (a larger wheel with a lower-profile tire) keeps the diameter the same while changing the look and handling; done wrong, it throws off the speedometer and can rub.
Frequently asked questions
What does 65 mean in a tire size? The aspect ratio — sidewall height is 65% of the tread width.
Can I change tire size? Within limits — keep the overall diameter close to stock to avoid speedometer and clearance issues.
What’s the load index? A coded number for the maximum weight the tire can safely carry.