285/65R18 vs 285/70R18
285/70R18 is outside the ±3% rule as a replacement for 285/65R18: the diameter differs by +3.44%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 285/70R18 on a car calibrated for 285/65R18, the speedometer reads 58.0 mph when you're really doing 60, and the odometer under-counts by 3.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.0 mph |
| 45 mph | 46.5 mph |
| 60 mph | 62.1 mph |
| 70 mph | 72.4 mph |
| 80 mph | 82.8 mph |
Other sizes close to 285/65R18
- 285/65R18 vs 275/65R18-1.57%
- 285/65R18 vs 275/70R18+1.75%
- 285/65R18 vs 285/70R17+0.37%
- 285/65R18 vs 265/65R18-3.14%
- 285/65R18 vs 265/70R18+0.06%
- 285/65R18 vs 255/70R18-1.63%
- 285/65R18 vs 255/65R18-4.71%
- 285/65R18 vs 33x12.50R18+1.27%
- 285/65R18 vs 285/60R18-3.44%
- 285/65R18 vs 305/65R18+3.14%
- 285/65R18 vs 275/60R18-4.89%
- 285/65R18 vs 305/60R18-0.54%
Questions
Can I replace 285/65R18 with 285/70R18?
285/70R18 is outside the ±3% rule as a replacement for 285/65R18: the diameter differs by +3.44%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 285/65R18 and 285/70R18?
285/70R18 is 1.12" taller and 0 mm wider; the sidewall is +0.56". At an indicated 60 mph you'd actually be doing 62.1 mph.
Will 285/70R18 fit on 285/65R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 285 mm tire and the fender clearance.