235/70R18 tire size
235/70R18 is a metric size: 31.0" tall, 9.3" wide, on a 18" rim — about a 31x9.50R18. The sidewall is 6.5" and the tire turns 652 times per mile.
235/70R18 specs
| Overall diameter (height) | 30.95" · 786 mm |
|---|---|
| Section width | 9.25" · 235 mm |
| Sidewall height | 6.48" · 165 mm (70% of width) |
| Rim diameter | 18" |
| Circumference | 97.24" · 2.470 m |
| Revolutions per mile | 652 (405 per km) |
| Inch (flotation) equivalent | 31x9.50R18 |
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" | +3.63% | +40 mm | 62.2 mph | calculate → |
| 265/60R18 common | 30.52" | -1.40% | +30 mm | 59.2 mph | calculate → |
| 245/60R18 common | 29.57" | -4.45% | +10 mm | 57.3 mph | calculate → |
| 265/65R18 common | 31.56" | +1.97% | +30 mm | 61.2 mph | calculate → |
| 235/65R18 common | 30.03" | -2.99% | 0 mm | 58.2 mph | calculate → |
| 255/70R18 common | 32.06" | +3.56% | +20 mm | 62.1 mph | calculate → |
| 255/65R18 common | 31.05" | +0.32% | +20 mm | 60.2 mph | calculate → |
| 255/60R18 | 30.05" | -2.93% | +20 mm | 58.2 mph | calculate → |
| 285/60R18 | 31.46" | +1.65% | +50 mm | 61.0 mph | calculate → |
| 275/60R18 | 30.99" | +0.13% | +40 mm | 60.1 mph | calculate → |
| 305/60R18 | 32.41" | +4.71% | +70 mm | 62.8 mph | calculate → |
| 245/75R18 | 32.47" | +4.90% | +10 mm | 62.9 mph | calculate → |
| 245/70R18 | 31.50" | +1.78% | +10 mm | 61.1 mph | calculate → |
| 165/90R18 | 29.69" | -4.07% | -70 mm | 57.6 mph | calculate → |
| 245/65R18 | 30.54" | -1.34% | +10 mm | 59.2 mph | calculate → |
| 175/90R18 | 30.40" | -1.78% | -60 mm | 58.9 mph | calculate → |
| 285/55R18 | 30.34" | -1.97% | +50 mm | 58.8 mph | calculate → |
| 275/55R18 | 29.91" | -3.37% | +40 mm | 58.0 mph | calculate → |
| 325/45R18 | 29.52" | -4.64% | +90 mm | 57.2 mph | calculate → |
| 225/65R18 | 29.52" | -4.64% | -10 mm | 57.2 mph | calculate → |
| 265/55R18 | 29.48" | -4.77% | +30 mm | 57.1 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" | +0.31% | +20 mm | 60.2 mph | calculate → |
| 255/70R17 common | 31.06" | +0.33% | +20 mm | 60.2 mph | calculate → |
| 235/75R17 | 30.88" | -0.24% | 0 mm | 59.9 mph | calculate → |
| 275/55R19 | 30.91" | -0.14% | +40 mm | 59.9 mph | calculate → |
| 275/65R17 | 31.07" | +0.39% | +40 mm | 60.2 mph | calculate → |
| 235/65R19 | 31.03" | +0.24% | 0 mm | 60.1 mph | calculate → |
| 31x10.50R17 | 31.00" | +0.15% | +32 mm | 60.1 mph | calculate → |
| 165/90R19 | 30.69" | -0.84% | -70 mm | 59.5 mph | calculate → |
Try another size against 235/70R18
Questions
What size is 235/70R18 in inches?
235/70R18 is about 31.0" tall and 9.3" wide on a 18-inch rim — roughly a 31x9.50R18 in inch sizing.
What does 235/70R18 mean?
235 mm section width, sidewall 70% of the width (6.48"), radial construction, 18-inch rim.
What tire sizes are equivalent to 235/70R18?
On the same 18" rim, within 3% of the diameter: 275/60R18 (+0.13%), 255/65R18 (+0.32%), 245/65R18 (-1.34%), 265/60R18 (-1.40%), 285/60R18 (+1.65%), 175/90R18 (-1.78%).
How many revolutions per mile does a 235/70R18 tire make?
About 652 revolutions per mile (circumference 97.2").
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.