How to Read a Tire Size
Every tire's size is molded on its sidewall, and the same size is printed on the tire placard inside your driver's door jamb. Take 225/65R17 102H as an example:
- 225 — section width in millimeters.
- 65 — aspect ratio: the sidewall is 65% as tall as the tire is wide.
- R — radial construction (D or a dash means bias-ply).
- 17 — rim diameter in inches: the wheel it fits.
- 102 — load index: 102 = 1,874 lb per tire (full chart).
- H — speed rating: H = up to 130 mph (full chart).
Prefixes
P (P-metric) is a passenger-car tire, LT a light-truck tire with higher inflation pressures and load ranges, ST a trailer-only tire, C after the size (205/75R16C) a commercial van tire. A plain metric size with no letter is a Euro-metric passenger tire.
Flotation sizes
Off-road sizes like 35x12.50R20 read overall diameter × section width in inches, then the rim diameter: a 35-inch-tall, 12.5-inch-wide tire for a 20-inch wheel.
Farm, industrial and lawn sizes
Sizes like 18.4-38 (width – rim), 10-16.5 or 20x10.00-8 (diameter x width – rim) follow the same idea; the ply rating or load range tells you the strength.
Other sidewall markings
M+S — mud and snow (all-season tread). 3PMSF (the mountain snowflake) — passed the severe-snow test. XL or Extra Load — higher load at higher pressure. Load Range E — 10-ply rated (chart). UTQG 500 A A — treadwear 500, traction A, temperature A. DOT ... 2324 — made in week 23 of 2024.
Find your size
Browse every size we stock, or open Tires and type the size from your sidewall.