225/35R20 vs 305/30R20
305/30R20 is outside the ±3% rule as a replacement for 225/35R20: the diameter differs by +3.83%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 305/30R20 on a car calibrated for 225/35R20, the speedometer reads 57.8 mph when you're really doing 60, and the odometer under-counts by 3.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.1 mph |
| 45 mph | 46.7 mph |
| 60 mph | 62.3 mph |
| 70 mph | 72.7 mph |
| 80 mph | 83.1 mph |
Other sizes close to 225/35R20
- 225/35R20 vs 235/40R19+0.77%
- 225/35R20 vs 255/35R19-0.66%
- 225/35R20 vs 245/35R20+2.10%
- 225/35R20 vs 255/35R20+3.16%
- 225/35R20 vs 225/40R19-0.44%
- 225/35R20 vs 265/35R19+0.39%
- 225/35R20 vs 285/30R20+2.03%
- 225/35R20 vs 275/30R20+1.13%
- 225/35R20 vs 265/35R20+4.21%
- 225/35R20 vs 235/35R20+1.05%
- 225/35R20 vs 295/30R20+2.93%
- 225/35R20 vs 305/30R19+0.02%
Questions
Can I replace 225/35R20 with 305/30R20?
305/30R20 is outside the ±3% rule as a replacement for 225/35R20: the diameter differs by +3.83%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 225/35R20 and 305/30R20?
305/30R20 is 1.00" taller and 80 mm wider; the sidewall is +0.50". At an indicated 60 mph you'd actually be doing 62.3 mph.
Will 305/30R20 fit on 225/35R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 305 mm tire and the fender clearance.