265/35R20 vs 255/40R20
255/40R20 is a safe swap for 265/35R20 by the usual ±3% rule: the diameter differs by +2.67%.
Speedometer and odometer
With 255/40R20 on a car calibrated for 265/35R20, the speedometer reads 58.4 mph when you're really doing 60, and the odometer under-counts by 2.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.8 mph |
| 45 mph | 46.2 mph |
| 60 mph | 61.6 mph |
| 70 mph | 71.9 mph |
| 80 mph | 82.1 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 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%
- 265/35R20 vs 295/30R20-1.23%
Questions
Can I replace 265/35R20 with 255/40R20?
255/40R20 is a safe swap for 265/35R20 by the usual ±3% rule: the diameter differs by +2.67%.
What's the difference between 265/35R20 and 255/40R20?
255/40R20 is 0.73" taller and 10 mm narrower; the sidewall is +0.36". At an indicated 60 mph you'd actually be doing 61.6 mph.
Will 255/40R20 fit on 265/35R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.