32x11.50R15 vs 33x12.50R15
33x12.50R15 is outside the ±3% rule as a replacement for 32x11.50R15: the diameter differs by +3.13%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Side by side
| 32x11.50R15 | 33x12.50R15 | Difference | |
|---|---|---|---|
| Overall diameter | 32.00" | 33.00" | +1.00" (+3.13%) |
| Section width | 292 mm | 318 mm | +26 mm |
| Sidewall | 8.50" | 9.00" | +0.50" |
| Rim | 15" | 15" | same |
| Circumference | 100.5" | 103.7" | +3.1" |
| Revs per mile | 630 | 611 | -19 |
| Ride height | — | — | +0.50" |
| Speedometer reads 60 mph | 60.0 | 61.9 | +1.9 mph |
Speedometer and odometer
With 33x12.50R15 on a car calibrated for 32x11.50R15, the speedometer reads 58.2 mph when you're really doing 60, and the odometer under-counts by 3.1%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.9 mph |
| 45 mph | 46.4 mph |
| 60 mph | 61.9 mph |
| 70 mph | 72.2 mph |
| 80 mph | 82.5 mph |
Other sizes close to 32x11.50R15
Questions
Can I replace 32x11.50R15 with 33x12.50R15?
33x12.50R15 is outside the ±3% rule as a replacement for 32x11.50R15: the diameter differs by +3.13%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 32x11.50R15 and 33x12.50R15?
33x12.50R15 is 1.00" taller and 26 mm wider; the sidewall is +0.50". At an indicated 60 mph you'd actually be doing 61.9 mph.
Will 33x12.50R15 fit on 32x11.50R15 wheels?
Both use a 15" rim, so the wheel diameter matches; check the wheel's width range for a 318 mm tire and the fender clearance.