Tire size
275/65R18 in inches
A 275/65R18 tire is 32.1 inches tall and 10.8 inches wide, on a 18-inch wheel. Written inch-style that is about 32.1x10.8R18 (an equivalent, not a size on sale). It rounds to a 32-inch tire.
| 275/65R18 | Inches | Metric |
|---|---|---|
| Overall diameter (height) | 32.1 in | 815 mm |
| Section width | 10.8 in | 275 mm |
| Sidewall height | 7.0 in | 179 mm |
| Wheel (rim) diameter | 18 in | 457 mm |
| Circumference | 100.8 in | 2559 mm |
| Revolutions | 629 per mile | 391 per km |
How it's worked out
The 65 means the sidewall is 65% of the 275 mm width: 178.8 mm, or 7.04 in. Height = wheel + 2 sidewalls = 18 + 2 x 7.04 = 32.1 in.
Similar sizes
Sizes within about 3.5% of the height of 275/65R18. The last column is your real speed at an indicated 60 mph if your speedometer was set for 275/65R18.
| Size | Height | vs 275/65R18 | Real speed at 60 mph shown |
|---|---|---|---|
| 255/75R17 | 32.1 in | -0.0% | 60.0 mph |
| 255/70R18 | 32.1 in | -0.1% | 60.0 mph |
| 285/45R22 | 32.1 in | +0.1% | 60.0 mph |
| 305/50R20 | 32.0 in | -0.2% | 59.9 mph |
| 32x11.50R15 | 32.0 in | -0.2% | 59.9 mph |
| 275/70R17 | 32.2 in | +0.3% | 60.2 mph |
| 275/55R20 | 31.9 in | -0.5% | 59.7 mph |
| 285/55R20 | 32.3 in | +0.8% | 60.5 mph |
Going bigger from 275/65R18
If 275/65R18 is your stock size, these are the commonly sold axle ratios that come closest to your stock overall gearing on bigger tires.
| Your ratio now | On 33s | On 35s | On 37s |
|---|---|---|---|
| 3.21 | 3.31 exact 3.30 | 3.55 exact 3.50 | 3.73 exact 3.70 |
| 3.42 | 3.55 exact 3.52 | 3.73 exact 3.73 | 3.91 exact 3.95 |
| 3.55 | 3.73 exact 3.65 | 3.91 exact 3.87 | 4.10 exact 4.10 |
| 3.73 | 3.91 exact 3.84 | 4.10 exact 4.07 | 4.30 exact 4.30 |
| 3.91 | 4.10 exact 4.02 | 4.30 exact 4.27 | 4.56 exact 4.51 |
| 4.10 | 4.30 exact 4.22 | 4.56 exact 4.47 | 4.88 exact 4.73 |
Exact = your ratio x new height / 32.1. Front and rear axles must match on a 4WD. Not every ratio is made for every axle. Want more pull than stock? Go one step shorter. More in the regearing guide.
Questions
How tall is a 275/65R18 tire in inches?
32.1 inches (815 mm). That is the nominal height: the 18-inch wheel plus two 7.04-inch sidewalls.
What is 275/65R18 in inches?
32.1x10.8R18: 32.1 inches tall, 10.8 inches wide, for a 18-inch wheel.
Is 275/65R18 a 32-inch tire?
It measures 32.1 inches on paper, so it rounds to 32. Real tires vary a little by brand, load and wear, so check the maker's spec sheet if a fraction of an inch matters.
How many revolutions per mile does 275/65R18 do?
About 629 per mile (391 per km), from its nominal circumference of 100.8 inches.
Nominal dimensions, calculated from the size marking. Real tires differ slightly by brand, rim width, pressure and wear. Fitment depends on your vehicle, lift and wheels: this page doesn't say whether a size fits. Updated 2026-11-14.