255/30R22 vs 285/30R22
285/30R22 is a safe swap for 255/30R22 by the usual ±3% rule: the diameter differs by +2.53%.
Speedometer and odometer
With 285/30R22 on a car calibrated for 255/30R22, the speedometer reads 58.5 mph when you're really doing 60, and the odometer under-counts by 2.5%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.8 mph |
| 45 mph | 46.1 mph |
| 60 mph | 61.5 mph |
| 70 mph | 71.8 mph |
| 80 mph | 82.0 mph |
Other sizes close to 255/30R22
Questions
Can I replace 255/30R22 with 285/30R22?
285/30R22 is a safe swap for 255/30R22 by the usual ±3% rule: the diameter differs by +2.53%.
What's the difference between 255/30R22 and 285/30R22?
285/30R22 is 0.71" taller and 30 mm wider; the sidewall is +0.35". At an indicated 60 mph you'd actually be doing 61.5 mph.
Will 285/30R22 fit on 255/30R22 wheels?
Both use a 22" rim, so the wheel diameter matches; check the wheel's width range for a 285 mm tire and the fender clearance.