275/65R18 Tire Size in Inches — Diameter, Width & Specs
A 275/65R18 tire is 32.07 inches tall (overall diameter), 10.83 inches wide, with a 7.04-inch sidewall, on a 18-inch wheel. In millimeters: 815 × 275.
Full specifications
| Measurement | Inches | Millimeters |
|---|---|---|
| Overall diameter | 32.07 in | 815 mm |
| Tire width | 10.83 in | 275 mm |
| Sidewall height | 7.04 in | 179 mm |
| Circumference | 100.8 in | 2559 mm |
| Revolutions per mile | 629 | |
| Wheel (rim) diameter | 18 in | 457 mm |
Same-diameter alternatives (18" rim)
No same-rim alternatives within ±1.5% in the common size list.
Popular comparisons with the 275/65R18
Load index & speed rating — how to read them
The size code is only half of the sidewall. After it comes a load index and a speed letter, like 121R. Load index 121 means one tire carries up to 3,197 lbs at its rated pressure; speed rating R means up to 106 mph. A replacement tire must meet or exceed both numbers on your vehicle's door-jamb placard. Calculate another size or compare two sizes.
How tall is a 275/65R18 tire?
32.07 inches overall diameter (815 mm), from the standard size formula. A specific brand's measured height can differ by a few tenths.
How wide is a 275/65R18?
10.83 inches (275 mm) at the casing's widest point, unloaded.
What does 275/65R18 convert to in flotation (inch) sizes?
Its diameter is 32.07", so the nearest flotation class is 32-inch tires (e.g. 32x12.50R18 where that size exists). Use the converter for exact near-matches.
Nominal geometry — method. Last verified November 12, 2026.