235/35R20 vs 285/30R20
285/30R20 is a safe swap for 235/35R20 by the usual ±3% rule: the diameter differs by +0.97%.
Speedometer and odometer
With 285/30R20 on a car calibrated for 235/35R20, the speedometer reads 59.4 mph when you're really doing 60, and the odometer under-counts by 1.0%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.3 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.6 mph |
| 70 mph | 70.7 mph |
| 80 mph | 80.8 mph |
Other sizes close to 235/35R20
- 235/35R20 vs 245/40R19+0.91%
- 235/35R20 vs 235/40R19-0.28%
- 235/35R20 vs 245/40R20+4.68%
- 235/35R20 vs 275/35R19+0.39%
- 235/35R20 vs 245/35R20+1.04%
- 235/35R20 vs 255/35R20+2.08%
- 235/35R20 vs 275/35R20+4.16%
- 235/35R20 vs 265/35R19-0.65%
- 235/35R20 vs 275/30R20+0.07%
- 235/35R20 vs 265/35R20+3.12%
- 235/35R20 vs 295/30R20+1.86%
- 235/35R20 vs 305/30R20+2.75%
Questions
Can I replace 235/35R20 with 285/30R20?
285/30R20 is a safe swap for 235/35R20 by the usual ±3% rule: the diameter differs by +0.97%.
What's the difference between 235/35R20 and 285/30R20?
285/30R20 is 0.26" taller and 50 mm wider; the sidewall is +0.13". At an indicated 60 mph you'd actually be doing 60.6 mph.
Will 285/30R20 fit on 235/35R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 285 mm tire and the fender clearance.