255/30R20 tire size
255/30R20 is a metric size: 26.0" tall, 10.0" wide, on a 20" rim — about a 26x10.00R20. The sidewall is 3.0" and the tire turns 775 times per mile.
255/30R20 specs
| Overall diameter (height) | 26.02" · 661 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 3.01" · 77 mm (30% of width) |
| Rim diameter | 20" |
| Circumference | 81.76" · 2.077 m |
| Revolutions per mile | 775 (482 per km) |
| Inch (flotation) equivalent | 26x10.00R20 |
Equivalent sizes on a 20" 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 | |
|---|---|---|---|---|---|
| 245/35R20 common | 26.75" | +2.80% | -10 mm | 61.7 mph | compare → |
| 255/35R20 common | 27.03" | +3.86% | 0 mm | 62.3 mph | compare → |
| 285/30R20 common | 26.73" | +2.72% | +30 mm | 61.6 mph | compare → |
| 275/30R20 common | 26.50" | +1.82% | +20 mm | 61.1 mph | compare → |
| 265/35R20 common | 27.30" | +4.92% | +10 mm | 63.0 mph | compare → |
| 235/35R20 | 26.48" | +1.74% | -20 mm | 61.0 mph | compare → |
| 295/30R20 | 26.97" | +3.63% | +40 mm | 62.2 mph | compare → |
| 305/30R20 | 27.20" | +4.54% | +50 mm | 62.7 mph | compare → |
| 245/30R20 | 25.79" | -0.91% | -10 mm | 59.5 mph | compare → |
| 265/30R20 | 26.26" | +0.91% | +10 mm | 60.5 mph | compare → |
| 225/35R20 | 26.20" | +0.68% | -30 mm | 60.4 mph | compare → |
| 335/25R20 | 26.59" | +2.19% | +80 mm | 61.3 mph | compare → |
| 235/30R20 | 25.55" | -1.82% | -20 mm | 58.9 mph | compare → |
| 305/25R20 | 26.00" | -0.08% | +50 mm | 60.0 mph | compare → |
| 295/25R20 | 25.81" | -0.83% | +40 mm | 59.5 mph | calculate → |
| 325/25R20 | 26.40" | +1.44% | +70 mm | 60.9 mph | calculate → |
| 285/25R20 | 25.61" | -1.59% | +30 mm | 59.0 mph | calculate → |
| 225/30R20 | 25.31" | -2.72% | -30 mm | 58.4 mph | calculate → |
| 345/25R20 | 26.79" | +2.95% | +90 mm | 61.8 mph | calculate → |
| 225/40R20 | 27.09" | +4.08% | -30 mm | 62.5 mph | calculate → |
| 275/25R20 | 25.41" | -2.34% | +20 mm | 58.6 mph | calculate → |
| 145/60R20 | 26.85" | +3.18% | -110 mm | 61.9 mph | calculate → |
| 155/60R20 | 27.32" | +4.99% | -100 mm | 63.0 mph | calculate → |
| 315/25R20 | 26.20" | +0.68% | +60 mm | 60.4 mph | calculate → |
| 215/30R20 | 25.08" | -3.63% | -40 mm | 57.8 mph | calculate → |
Plus / minus sizing: 19" and 21" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
Try another size against 255/30R20
Questions
What size is 255/30R20 in inches?
255/30R20 is about 26.0" tall and 10.0" wide on a 20-inch rim — roughly a 26x10.00R20 in inch sizing.
What does 255/30R20 mean?
255 mm section width, sidewall 30% of the width (3.01"), radial construction, 20-inch rim.
What tire sizes are equivalent to 255/30R20?
On the same 20" rim, within 3% of the diameter: 305/25R20 (-0.08%), 225/35R20 (+0.68%), 315/25R20 (+0.68%), 295/25R20 (-0.83%), 265/30R20 (+0.91%), 245/30R20 (-0.91%).
How many revolutions per mile does a 255/30R20 tire make?
About 775 revolutions per mile (circumference 81.8").
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.