235/65R18 tire size
235/65R18 is a metric size: 30.0" tall, 9.3" wide, on a 18" rim — about a 30x9.50R18. The sidewall is 6.0" and the tire turns 672 times per mile.
235/65R18 specs
| Overall diameter (height) | 30.03" · 763 mm |
|---|---|
| Section width | 9.25" · 235 mm |
| Sidewall height | 6.01" · 153 mm (65% of width) |
| Rim diameter | 18" |
| Circumference | 94.33" · 2.396 m |
| Revolutions per mile | 672 (417 per km) |
| Inch (flotation) equivalent | 30x9.50R18 |
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 | |
|---|---|---|---|---|---|
| 235/60R18 common | 29.10" | -3.08% | 0 mm | 58.2 mph | compare → |
| 265/60R18 common | 30.52" | +1.64% | +30 mm | 61.0 mph | compare → |
| 225/60R18 common | 28.63" | -4.65% | -10 mm | 57.2 mph | compare → |
| 245/60R18 common | 29.57" | -1.51% | +10 mm | 59.1 mph | compare → |
| 255/55R18 common | 29.04" | -3.28% | +20 mm | 58.0 mph | compare → |
| 255/65R18 common | 31.05" | +3.41% | +20 mm | 62.0 mph | compare → |
| 255/60R18 | 30.05" | +0.07% | +20 mm | 60.0 mph | compare → |
| 245/55R18 | 28.61" | -4.72% | +10 mm | 57.2 mph | compare → |
| 285/60R18 | 31.46" | +4.79% | +50 mm | 62.9 mph | compare → |
| 275/60R18 | 30.99" | +3.21% | +40 mm | 61.9 mph | compare → |
| 155/90R18 | 28.98" | -3.47% | -80 mm | 57.9 mph | calculate → |
| 165/90R18 | 29.69" | -1.11% | -70 mm | 59.3 mph | calculate → |
| 285/50R18 | 29.22" | -2.69% | +50 mm | 58.4 mph | calculate → |
| 305/45R18 | 28.81" | -4.06% | +70 mm | 57.6 mph | calculate → |
| 245/70R18 | 31.50" | +4.92% | +10 mm | 63.0 mph | calculate → |
| 275/55R18 | 29.91" | -0.39% | +40 mm | 59.8 mph | calculate → |
| 285/55R18 | 30.34" | +1.05% | +50 mm | 60.6 mph | calculate → |
| 175/90R18 | 30.40" | +1.25% | -60 mm | 60.7 mph | calculate → |
| 245/65R18 | 30.54" | +1.70% | +10 mm | 61.0 mph | calculate → |
| 325/45R18 | 29.52" | -1.70% | +90 mm | 59.0 mph | calculate → |
| 235/70R18 | 30.95" | +3.08% | 0 mm | 61.8 mph | calculate → |
| 225/65R18 | 29.52" | -1.70% | -10 mm | 59.0 mph | calculate → |
| 265/55R18 | 29.48" | -1.84% | +30 mm | 58.9 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 | |
|---|---|---|---|---|---|
| 255/55R19 common | 30.04" | +0.05% | +20 mm | 60.0 mph | compare → |
| 255/65R17 common | 30.05" | +0.08% | +20 mm | 60.0 mph | compare → |
| 235/70R17 | 29.95" | -0.25% | 0 mm | 59.9 mph | compare → |
| 275/50R19 | 29.83" | -0.67% | +40 mm | 59.6 mph | compare → |
| 225/75R17 | 30.29" | +0.87% | -10 mm | 60.5 mph | compare → |
| 275/60R17 | 29.99" | -0.12% | +40 mm | 59.9 mph | calculate → |
| 235/60R19 | 30.10" | +0.25% | 0 mm | 60.1 mph | calculate → |
| 175/80R19 | 30.02" | -0.01% | -60 mm | 60.0 mph | calculate → |
Try another size against 235/65R18
Questions
What size is 235/65R18 in inches?
235/65R18 is about 30.0" tall and 9.3" wide on a 18-inch rim — roughly a 30x9.50R18 in inch sizing.
What does 235/65R18 mean?
235 mm section width, sidewall 65% of the width (6.01"), radial construction, 18-inch rim.
What tire sizes are equivalent to 235/65R18?
On the same 18" rim, within 3% of the diameter: 255/60R18 (+0.07%), 275/55R18 (-0.39%), 285/55R18 (+1.05%), 165/90R18 (-1.11%), 175/90R18 (+1.25%), 245/60R18 (-1.51%).
How many revolutions per mile does a 235/65R18 tire make?
About 672 revolutions per mile (circumference 94.3").
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.