255/35R21 tire size
255/35R21 is a metric size: 28.0" tall, 10.0" wide, on a 21" rim — about a 28x10.00R21. The sidewall is 3.5" and the tire turns 720 times per mile.
255/35R21 specs
| Overall diameter (height) | 28.03" · 712 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 3.51" · 89 mm (35% of width) |
| Rim diameter | 21" |
| Circumference | 88.05" · 2.236 m |
| Revolutions per mile | 720 (447 per km) |
| Inch (flotation) equivalent | 28x10.00R21 |
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 | |
|---|---|---|---|---|---|
| 265/40R21 common | 29.35" | +4.71% | +10 mm | 62.8 mph | compare → |
| 275/35R21 common | 28.58" | +1.97% | +20 mm | 61.2 mph | compare → |
| 295/35R21 | 29.13" | +3.93% | +40 mm | 62.4 mph | compare → |
| 255/40R21 | 29.03" | +3.58% | 0 mm | 62.1 mph | compare → |
| 265/35R21 | 28.30" | +0.98% | +10 mm | 60.6 mph | compare → |
| 245/35R21 | 27.75" | -0.98% | -10 mm | 59.4 mph | compare → |
| 325/30R21 | 28.68" | +2.32% | +70 mm | 61.4 mph | compare → |
| 315/30R21 | 28.44" | +1.47% | +60 mm | 60.9 mph | compare → |
| 285/35R21 | 28.85" | +2.95% | +30 mm | 61.8 mph | compare → |
| 245/40R21 | 28.72" | +2.46% | -10 mm | 61.5 mph | compare → |
| 295/30R21 | 27.97" | -0.21% | +40 mm | 59.9 mph | compare → |
| 305/30R21 | 28.20" | +0.63% | +50 mm | 60.4 mph | compare → |
| 285/30R21 | 27.73" | -1.05% | +30 mm | 59.4 mph | compare → |
| 275/30R21 | 27.50" | -1.90% | +20 mm | 58.9 mph | compare → |
| 255/30R21 | 27.02" | -3.58% | 0 mm | 57.9 mph | calculate → |
| 355/25R21 | 27.99" | -0.14% | +100 mm | 59.9 mph | calculate → |
| 235/45R21 | 29.33" | +4.64% | -20 mm | 62.8 mph | calculate → |
| 295/25R21 | 26.81" | -4.35% | +40 mm | 57.4 mph | calculate → |
| 335/30R21 | 28.91" | +3.16% | +80 mm | 61.9 mph | calculate → |
| 305/35R21 | 29.41" | +4.92% | +50 mm | 62.9 mph | calculate → |
| 265/30R21 | 27.26" | -2.74% | +10 mm | 58.4 mph | calculate → |
| 345/30R21 | 29.15" | +4.00% | +90 mm | 62.4 mph | calculate → |
| 345/25R21 | 27.79" | -0.84% | +90 mm | 59.5 mph | calculate → |
| 325/25R21 | 27.40" | -2.25% | +70 mm | 58.7 mph | calculate → |
| 225/45R21 | 28.97" | +3.37% | -30 mm | 62.0 mph | calculate → |
| 305/25R21 | 27.00" | -3.65% | +50 mm | 57.8 mph | calculate → |
| 245/30R21 | 26.79" | -4.42% | -10 mm | 57.3 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 | |
|---|---|---|---|---|---|
| 255/40R20 common | 28.03" | +0.01% | 0 mm | 60.0 mph | compare → |
| 285/35R20 common | 27.85" | -0.62% | +30 mm | 59.6 mph | compare → |
| 295/35R20 | 28.13" | +0.37% | +40 mm | 60.2 mph | compare → |
| 255/30R22 | 28.02" | -0.01% | 0 mm | 60.0 mph | compare → |
| 295/25R22 | 27.81" | -0.79% | +40 mm | 59.5 mph | compare → |
| 265/30R22 | 28.26" | +0.83% | +10 mm | 60.5 mph | compare → |
| 335/30R20 | 27.91" | -0.41% | +80 mm | 59.8 mph | calculate → |
| 345/30R20 | 28.15" | +0.44% | +90 mm | 60.3 mph | calculate → |
| 245/30R22 | 27.79" | -0.86% | -10 mm | 59.5 mph | calculate → |
| 315/25R22 | 28.20" | +0.62% | +60 mm | 60.4 mph | calculate → |
| 305/25R22 | 28.00" | -0.08% | +50 mm | 59.9 mph | calculate → |
| 225/45R20 | 27.97" | -0.20% | -30 mm | 59.9 mph | calculate → |
| 155/65R20 | 27.93" | -0.34% | -100 mm | 59.8 mph | calculate → |
| 165/60R20 | 27.80" | -0.83% | -90 mm | 59.5 mph | calculate → |
Try another size against 255/35R21
Questions
What size is 255/35R21 in inches?
255/35R21 is about 28.0" tall and 10.0" wide on a 21-inch rim — roughly a 28x10.00R21 in inch sizing.
What does 255/35R21 mean?
255 mm section width, sidewall 35% of the width (3.51"), radial construction, 21-inch rim.
What tire sizes are equivalent to 255/35R21?
On the same 21" rim, within 3% of the diameter: 355/25R21 (-0.14%), 295/30R21 (-0.21%), 305/30R21 (+0.63%), 345/25R21 (-0.84%), 245/35R21 (-0.98%), 265/35R21 (+0.98%).
How many revolutions per mile does a 255/35R21 tire make?
About 720 revolutions per mile (circumference 88.1").
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.