305/40R22 vs 33x12.50R22
33x12.50R22 is outside the ±3% rule as a replacement for 305/40R22: the diameter differs by +4.41%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Side by side
| 305/40R22 | 33x12.50R22 | Difference | |
|---|---|---|---|
| Overall diameter | 31.61" | 33.00" | +1.39" (+4.41%) |
| Section width | 305 mm | 318 mm | +13 mm |
| Sidewall | 4.80" | 5.50" | +0.70" |
| Rim | 22" | 22" | same |
| Circumference | 99.3" | 103.7" | +4.4" |
| Revs per mile | 638 | 611 | -27 |
| Ride height | — | — | +0.70" |
| Speedometer reads 60 mph | 60.0 | 62.6 | +2.6 mph |
Speedometer and odometer
With 33x12.50R22 on a car calibrated for 305/40R22, the speedometer reads 57.5 mph when you're really doing 60, and the odometer under-counts by 4.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.3 mph |
| 45 mph | 47.0 mph |
| 60 mph | 62.6 mph |
| 70 mph | 73.1 mph |
| 80 mph | 83.5 mph |
Other sizes close to 305/40R22
- 305/40R22 vs 285/45R22+1.56%
- 305/40R22 vs 275/50R22+3.86%
- 305/40R22 vs 275/40R22-2.99%
- 305/40R22 vs 265/40R22-3.99%
- 305/40R22 vs 285/40R22-1.99%
- 305/40R22 vs 305/45R22+3.80%
- 305/40R22 vs 275/45R22+0.44%
- 305/40R22 vs 325/35R22-2.06%
- 305/40R22 vs 315/35R22-2.93%
- 305/40R22 vs 295/35R22-4.67%
- 305/40R22 vs 295/40R22-1.00%
- 305/40R22 vs 255/40R22-4.98%
Questions
Can I replace 305/40R22 with 33x12.50R22?
33x12.50R22 is outside the ±3% rule as a replacement for 305/40R22: the diameter differs by +4.41%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 305/40R22 and 33x12.50R22?
33x12.50R22 is 1.39" taller and 13 mm wider; the sidewall is +0.70". At an indicated 60 mph you'd actually be doing 62.6 mph.
Will 33x12.50R22 fit on 305/40R22 wheels?
Both use a 22" rim, so the wheel diameter matches; check the wheel's width range for a 318 mm tire and the fender clearance.