265/35R20 vs 305/35R20
305/35R20 is outside the ±3% rule as a replacement for 265/35R20: the diameter differs by +4.04%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 305/35R20 on a car calibrated for 265/35R20, the speedometer reads 57.7 mph when you're really doing 60, and the odometer under-counts by 4.0%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.2 mph |
| 45 mph | 46.8 mph |
| 60 mph | 62.4 mph |
| 70 mph | 72.8 mph |
| 80 mph | 83.2 mph |
Other sizes close to 265/35R20
- 265/35R20 vs 255/40R19-0.99%
- 265/35R20 vs 275/40R20+4.97%
- 265/35R20 vs 245/40R20+1.51%
- 265/35R20 vs 245/35R20-2.02%
- 265/35R20 vs 255/35R20-1.01%
- 265/35R20 vs 275/35R20+1.01%
- 265/35R20 vs 255/40R20+2.67%
- 265/35R20 vs 235/45R19+0.09%
- 265/35R20 vs 285/35R20+2.02%
- 265/35R20 vs 285/30R20-2.09%
- 265/35R20 vs 275/30R20-2.96%
- 265/35R20 vs 235/35R20-3.03%
Questions
Can I replace 265/35R20 with 305/35R20?
305/35R20 is outside the ±3% rule as a replacement for 265/35R20: the diameter differs by +4.04%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 265/35R20 and 305/35R20?
305/35R20 is 1.10" taller and 40 mm wider; the sidewall is +0.55". At an indicated 60 mph you'd actually be doing 62.4 mph.
Will 305/35R20 fit on 265/35R20 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.