235/65R18 dimensions
| Measure | Inches | Millimetres |
|---|---|---|
| Overall height | 30.03 in | 763 mm |
| Section width | 9.25 in | 235 mm |
| Sidewall height | 6.01 in | 152.8 mm |
| Wheel diameter | 18 in | 457 mm |
| Circumference | 94.3 in | 2,396 mm |
| Revolutions per mile | 671.7 |
The math
| Step | Math | Result |
|---|---|---|
| Sidewall | 235 × 65% = 152.8 mm ÷ 25.4 | 6.01 in |
| Overall height | 18 + 2 × 6.01 | 30.03 in |
| Width | 235 mm ÷ 25.4 | 9.25 in |
| Circumference | π × 30.03 | 94.3 in |
| Revs per mile | 63,360 ÷ 94.3 | 671.7 |
With a 6.0 in sidewall this is a tall sidewall with more cushion and flex. Real tires vary by brand and model, and the loaded radius under the vehicle is a bit smaller than this unloaded figure.
One step either way on a 18 in wheel
Each row changes one thing and shows the height change against 235/65R18, plus what 60 mph on the speedometer would really be if you swapped to that size.
| Change | Size | Height | Height change | 60 mph shows as | Verdict |
|---|---|---|---|---|---|
| Wider | 245/65R18 (compare) | 30.5 in | +1.7% | 61.0 mph | Close match |
| Narrower | 225/65R18 (compare) | 29.5 in | -1.7% | 59.0 mph | Close match |
| Taller sidewall | 235/70R18 (compare) | 31.0 in | +3.1% | 61.8 mph | Check clearance |
| Shorter sidewall | 235/60R18 (compare) | 29.1 in | -3.1% | 58.2 mph | Check clearance |
| Wider, shorter sidewall | 245/60R18 (compare) | 29.6 in | -1.5% | 59.1 mph | Close match |
| Narrower, taller sidewall | 225/70R18 (compare) | 30.4 in | +1.2% | 60.7 mph | Close match |
Calculated sizes within ±3% on other wheels
Plus and minus sizes that keep the overall height within about 3% (a rule of thumb from Discount Tire and 1010tires), widths within 30 mm. Calculated, not a list of tires on sale: check that a tire exists in that size.
17 in wheels (one wheel size smaller)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 255/65R17 (compare) | 30.1 in | +0.1% | +20 mm |
| 235/70R17 (compare) | 30.0 in | -0.2% | +0 mm |
| 205/80R17 (compare) | 29.9 in | -0.4% | -30 mm |
| 225/75R17 (compare) | 30.3 in | +0.9% | -10 mm |
19 in wheels (one wheel size larger)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 255/55R19 (compare) | 30.0 in | +0.1% | +20 mm |
| 215/65R19 (compare) | 30.0 in | -0.1% | -20 mm |
| 235/60R19 (compare) | 30.1 in | +0.2% | +0 mm |
| 205/70R19 (compare) | 30.3 in | +0.9% | -30 mm |
20 in wheels (two wheel sizes larger)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 255/50R20 (compare) | 30.0 in | +0.0% | +20 mm |
| 215/60R20 (compare) | 30.2 in | +0.4% | -20 mm |
| 235/55R20 (compare) | 30.2 in | +0.5% | +0 mm |
| 225/55R20 (compare) | 29.7 in | -0.9% | -10 mm |
Try it with your numbers
Compare 235/65R18 with another size · Convert to metric or find a 33 in size · Sizes that fit my wheel
Calculated from the size alone. Real tires vary a little by brand and model, and the loaded radius is a bit smaller. Confirm the wheel width range, clearance, load index and speed rating for your vehicle. See how to read a tire size, the load index chart and the speed rating chart.
Browse: all sizes in inches · 235/60R18 · 245/40R18.