Tire size
275/45R20 in inches
A 275/45R20 tire is 29.7 inches tall and 10.8 inches wide, on a 20-inch wheel. Written inch-style that is about 29.7x10.8R20 (an equivalent, not a size on sale). It rounds to a 30-inch tire.
| 275/45R20 | Inches | Metric |
|---|---|---|
| Overall diameter (height) | 29.7 in | 756 mm |
| Section width | 10.8 in | 275 mm |
| Sidewall height | 4.9 in | 124 mm |
| Wheel (rim) diameter | 20 in | 508 mm |
| Circumference | 93.4 in | 2373 mm |
| Revolutions | 678 per mile | 421 per km |
How it's worked out
The 45 means the sidewall is 45% of the 275 mm width: 123.8 mm, or 4.87 in. Height = wheel + 2 sidewalls = 20 + 2 x 4.87 = 29.7 in.
Similar sizes
Sizes within about 3.5% of the height of 275/45R20. The last column is your real speed at an indicated 60 mph if your speedometer was set for 275/45R20.
| Size | Height | vs 275/45R20 | Real speed at 60 mph shown |
|---|---|---|---|
| 245/60R18 | 29.6 in | -0.6% | 59.7 mph |
| 245/65R17 | 29.5 in | -0.7% | 59.6 mph |
| 245/70R16 | 29.5 in | -0.8% | 59.5 mph |
| 255/60R18 | 30.0 in | +1.0% | 60.6 mph |
| 255/65R17 | 30.1 in | +1.0% | 60.6 mph |
| 255/70R16 | 30.1 in | +1.0% | 60.6 mph |
| 255/75R15 | 30.1 in | +1.1% | 60.6 mph |
| 225/75R16 | 29.3 in | -1.5% | 59.1 mph |
Going bigger from 275/45R20
If 275/45R20 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 | 3.55 exact 3.56 | 3.73 exact 3.78 | 3.91 exact 3.99 |
| 3.42 | 3.73 exact 3.79 | 4.10 exact 4.02 | 4.30 exact 4.25 |
| 3.55 | 3.91 exact 3.94 | 4.10 exact 4.18 | 4.30 exact 4.42 |
| 3.73 | 4.10 exact 4.14 | 4.30 exact 4.39 | 4.56 exact 4.64 |
| 3.91 | 4.30 exact 4.34 | 4.56 exact 4.60 | 4.88 exact 4.86 |
| 4.10 | 4.56 exact 4.55 | 4.88 exact 4.82 | 5.13 exact 5.10 |
Exact = your ratio x new height / 29.7. 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 275/45R20 tire in inches?
29.7 inches (756 mm). That is the nominal height: the 20-inch wheel plus two 4.87-inch sidewalls.
What is 275/45R20 in inches?
29.7x10.8R20: 29.7 inches tall, 10.8 inches wide, for a 20-inch wheel.
Is 275/45R20 a 30-inch tire?
It measures 29.7 inches on paper, so it rounds to 30. 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 275/45R20 do?
About 678 per mile (421 per km), from its nominal circumference of 93.4 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.