285/65R20 vs 35x12.50R20
35x12.50R20 is a safe swap for 285/65R20 by the usual ±3% rule: the diameter differs by +1.20%.
Side by side
| 285/65R20 | 35x12.50R20 | Difference | |
|---|---|---|---|
| Overall diameter | 34.59" | 35.00" | +0.41" (+1.20%) |
| Section width | 285 mm | 318 mm | +33 mm |
| Sidewall | 7.29" | 7.50" | +0.21" |
| Rim | 20" | 20" | same |
| Circumference | 108.7" | 110.0" | +1.3" |
| Revs per mile | 583 | 576 | -7 |
| Ride height | — | — | +0.21" |
| Speedometer reads 60 mph | 60.0 | 60.7 | +0.7 mph |
Speedometer and odometer
With 35x12.50R20 on a car calibrated for 285/65R20, the speedometer reads 59.3 mph when you're really doing 60, and the odometer under-counts by 1.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.4 mph |
| 45 mph | 45.5 mph |
| 60 mph | 60.7 mph |
| 70 mph | 70.8 mph |
| 80 mph | 81.0 mph |
Other sizes close to 285/65R20
Questions
Can I replace 285/65R20 with 35x12.50R20?
35x12.50R20 is a safe swap for 285/65R20 by the usual ±3% rule: the diameter differs by +1.20%.
What's the difference between 285/65R20 and 35x12.50R20?
35x12.50R20 is 0.41" taller and 33 mm wider; the sidewall is +0.21". At an indicated 60 mph you'd actually be doing 60.7 mph.
Will 35x12.50R20 fit on 285/65R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 318 mm tire and the fender clearance.