255/65R18 tire size
255/65R18 is a metric size: 31.1" tall, 10.0" wide, on a 18" rim — about a 31x10.00R18. The sidewall is 6.5" and the tire turns 650 times per mile.
255/65R18 specs
| Overall diameter (height) | 31.05" · 789 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 6.53" · 166 mm (65% of width) |
| Rim diameter | 18" |
| Circumference | 97.55" · 2.478 m |
| Revolutions per mile | 650 (404 per km) |
| Inch (flotation) equivalent | 31x10.00R18 |
Equivalent sizes on a 18" 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 | |
|---|---|---|---|---|---|
| 275/65R18 common | 32.07" | +3.30% | +20 mm | 62.0 mph | compare → |
| 265/60R18 common | 30.52" | -1.71% | +10 mm | 59.0 mph | compare → |
| 245/60R18 common | 29.57" | -4.75% | -10 mm | 57.1 mph | compare → |
| 265/65R18 common | 31.56" | +1.65% | +10 mm | 61.0 mph | compare → |
| 235/65R18 common | 30.03" | -3.30% | -20 mm | 58.0 mph | compare → |
| 255/70R18 common | 32.06" | +3.23% | 0 mm | 61.9 mph | compare → |
| 285/65R18 common | 32.59" | +4.94% | +30 mm | 63.0 mph | compare → |
| 255/60R18 | 30.05" | -3.23% | 0 mm | 58.1 mph | compare → |
| 285/60R18 | 31.46" | +1.33% | +30 mm | 60.8 mph | compare → |
| 275/60R18 | 30.99" | -0.19% | +20 mm | 59.9 mph | compare → |
| 305/60R18 | 32.41" | +4.37% | +50 mm | 62.6 mph | compare → |
| 245/75R18 | 32.47" | +4.56% | -10 mm | 62.7 mph | calculate → |
| 245/70R18 | 31.50" | +1.46% | -10 mm | 60.9 mph | calculate → |
| 165/90R18 | 29.69" | -4.37% | -90 mm | 57.4 mph | calculate → |
| 235/70R18 | 30.95" | -0.32% | -20 mm | 59.8 mph | calculate → |
| 245/65R18 | 30.54" | -1.65% | -10 mm | 59.0 mph | calculate → |
| 175/90R18 | 30.40" | -2.09% | -80 mm | 58.7 mph | calculate → |
| 285/55R18 | 30.34" | -2.28% | +30 mm | 58.6 mph | calculate → |
| 275/55R18 | 29.91" | -3.68% | +20 mm | 57.8 mph | calculate → |
| 325/45R18 | 29.52" | -4.94% | +70 mm | 57.0 mph | calculate → |
| 225/65R18 | 29.52" | -4.94% | -30 mm | 57.0 mph | calculate → |
Plus / minus sizing: 17" and 19" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 255/60R19 common | 31.05" | -0.01% | 0 mm | 60.0 mph | compare → |
| 255/70R17 common | 31.06" | +0.01% | 0 mm | 60.0 mph | compare → |
| 235/75R17 | 30.88" | -0.56% | -20 mm | 59.7 mph | compare → |
| 275/55R19 | 30.91" | -0.46% | +20 mm | 59.7 mph | compare → |
| 275/65R17 | 31.07" | +0.08% | +20 mm | 60.0 mph | calculate → |
| 235/65R19 | 31.03" | -0.08% | -20 mm | 60.0 mph | calculate → |
| 31x10.50R17 | 31.00" | -0.16% | +12 mm | 59.9 mph | calculate → |
Try another size against 255/65R18
Questions
What size is 255/65R18 in inches?
255/65R18 is about 31.1" tall and 10.0" wide on a 18-inch rim — roughly a 31x10.00R18 in inch sizing.
What does 255/65R18 mean?
255 mm section width, sidewall 65% of the width (6.53"), radial construction, 18-inch rim.
What tire sizes are equivalent to 255/65R18?
On the same 18" rim, within 3% of the diameter: 275/60R18 (-0.19%), 235/70R18 (-0.32%), 285/60R18 (+1.33%), 245/70R18 (+1.46%), 265/65R18 (+1.65%), 245/65R18 (-1.65%).
How many revolutions per mile does a 255/65R18 tire make?
About 650 revolutions per mile (circumference 97.6").
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.