245/70R18 tire size
245/70R18 is a metric size: 31.5" tall, 9.6" wide, on a 18" rim — about a 31.5x9.50R18. The sidewall is 6.8" and the tire turns 640 times per mile.
245/70R18 specs
| Overall diameter (height) | 31.50" · 800 mm |
|---|---|
| Section width | 9.65" · 245 mm |
| Sidewall height | 6.75" · 172 mm (70% of width) |
| Rim diameter | 18" |
| Circumference | 98.97" · 2.514 m |
| Revolutions per mile | 640 (398 per km) |
| Inch (flotation) equivalent | 31.5x9.50R18 |
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" | +1.81% | +30 mm | 61.1 mph | calculate → |
| 265/60R18 common | 30.52" | -3.12% | +20 mm | 58.1 mph | calculate → |
| 265/65R18 common | 31.56" | +0.19% | +20 mm | 60.1 mph | calculate → |
| 265/70R18 common | 32.61" | +3.50% | +20 mm | 62.1 mph | calculate → |
| 235/65R18 common | 30.03" | -4.69% | -10 mm | 57.2 mph | calculate → |
| 255/70R18 common | 32.06" | +1.75% | +10 mm | 61.0 mph | calculate → |
| 255/65R18 common | 31.05" | -1.44% | +10 mm | 59.1 mph | calculate → |
| 285/65R18 common | 32.59" | +3.44% | +40 mm | 62.1 mph | calculate → |
| 255/60R18 | 30.05" | -4.62% | +10 mm | 57.2 mph | calculate → |
| 33x12.50R18 | 33.00" | +4.75% | +73 mm | 62.8 mph | calculate → |
| 285/60R18 | 31.46" | -0.12% | +40 mm | 59.9 mph | calculate → |
| 275/60R18 | 30.99" | -1.62% | +30 mm | 59.0 mph | calculate → |
| 305/60R18 | 32.41" | +2.87% | +60 mm | 61.7 mph | calculate → |
| 245/75R18 | 32.47" | +3.06% | 0 mm | 61.8 mph | calculate → |
| 235/70R18 | 30.95" | -1.75% | -10 mm | 59.0 mph | calculate → |
| 245/65R18 | 30.54" | -3.06% | 0 mm | 58.2 mph | calculate → |
| 175/90R18 | 30.40" | -3.50% | -70 mm | 57.9 mph | calculate → |
| 285/55R18 | 30.34" | -3.69% | +40 mm | 57.8 mph | calculate → |
| 235/80R18 | 32.80" | +4.12% | -10 mm | 62.5 mph | calculate → |
| 33x11.50R18 | 33.00" | +4.75% | +47 mm | 62.8 mph | calculate → |
| 33x13.50R18 | 33.00" | +4.75% | +98 mm | 62.8 mph | calculate → |
| 33x13.00R18 | 33.00" | +4.75% | +85 mm | 62.8 mph | calculate → |
| 33x10.50R18 | 33.00" | +4.75% | +22 mm | 62.8 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 | |
|---|---|---|---|---|---|
| 265/70R17 common | 31.61" | +0.32% | +20 mm | 60.2 mph | calculate → |
| 245/75R17 common | 31.47" | -0.11% | 0 mm | 59.9 mph | calculate → |
| 235/80R17 common | 31.80" | +0.95% | -10 mm | 60.6 mph | calculate → |
| 285/65R17 | 31.59" | +0.26% | +40 mm | 60.2 mph | calculate → |
Try another size against 245/70R18
Questions
What size is 245/70R18 in inches?
245/70R18 is about 31.5" tall and 9.6" wide on a 18-inch rim — roughly a 31.5x9.50R18 in inch sizing.
What does 245/70R18 mean?
245 mm section width, sidewall 70% of the width (6.75"), radial construction, 18-inch rim.
What tire sizes are equivalent to 245/70R18?
On the same 18" rim, within 3% of the diameter: 285/60R18 (-0.12%), 265/65R18 (+0.19%), 255/65R18 (-1.44%), 275/60R18 (-1.62%), 235/70R18 (-1.75%), 255/70R18 (+1.75%).
How many revolutions per mile does a 245/70R18 tire make?
About 640 revolutions per mile (circumference 99.0").
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.