275/20R21 tire size
275/20R21 is a metric size: 25.3" tall, 10.8" wide, on a 21" rim — about a 25.5x11.00R21. The sidewall is 2.2" and the tire turns 796 times per mile.
275/20R21 specs
| Overall diameter (height) | 25.33" · 643 mm |
|---|---|
| Section width | 10.83" · 275 mm |
| Sidewall height | 2.17" · 55 mm (20% of width) |
| Rim diameter | 21" |
| Circumference | 79.58" · 2.021 m |
| Revolutions per mile | 796 (495 per km) |
| Inch (flotation) equivalent | 25.5x11.00R21 |
Equivalent sizes on a 21" rim
Sizes within ±5% of the overall diameter. Green rows are inside the usual ±3% limit for keeping the speedometer, ABS and gearing right; red rows are bigger changes that need clearance checks.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 275/25R21 | 26.41" | +4.27% | 0 mm | 62.6 mph | calculate → |
Plus / minus sizing: 20" and 22" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 235/30R20 | 25.55" | +0.87% | -40 mm | 60.5 mph | calculate → |
| 225/30R20 | 25.31" | -0.06% | -50 mm | 60.0 mph | calculate → |
| 275/25R20 | 25.41" | +0.33% | 0 mm | 60.2 mph | calculate → |
| 215/30R20 | 25.08" | -0.99% | -60 mm | 59.4 mph | calculate → |
Try another size against 275/20R21
Questions
What size is 275/20R21 in inches?
275/20R21 is about 25.3" tall and 10.8" wide on a 21-inch rim — roughly a 25.5x11.00R21 in inch sizing.
What does 275/20R21 mean?
275 mm section width, sidewall 20% of the width (2.17"), radial construction, 21-inch rim.
What tire sizes are equivalent to 275/20R21?
On the same 21" rim, within 3% of the diameter: 275/25R21 (+4.27%).
How many revolutions per mile does a 275/20R21 tire make?
About 796 revolutions per mile (circumference 79.6").
How these numbers are computed
Diameter = rim + 2 × sidewall, sidewall = width × aspect ÷ 100, circumference = π × diameter, revolutions per mile = 63,360 ÷ circumference. Real tires differ by brand by a few tenths of an inch. Last reviewed October 14, 2026.