295/35R20 vs 305/40R20
305/40R20 is outside the ±3% rule as a replacement for 295/35R20: the diameter differs by +5.25%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 305/40R20 on a car calibrated for 295/35R20, the speedometer reads 57.0 mph when you're really doing 60, and the odometer under-counts by 5.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.6 mph |
| 45 mph | 47.4 mph |
| 60 mph | 63.1 mph |
| 70 mph | 73.7 mph |
| 80 mph | 84.2 mph |
Other sizes close to 295/35R20
- 295/35R20 vs 245/45R20+1.96%
- 295/35R20 vs 255/45R20+3.22%
- 295/35R20 vs 275/40R20+1.89%
- 295/35R20 vs 245/40R20-1.47%
- 295/35R20 vs 255/45R19-0.34%
- 295/35R20 vs 245/35R20-4.90%
- 295/35R20 vs 255/35R20-3.92%
- 295/35R20 vs 255/40R20-0.35%
- 295/35R20 vs 275/35R20-1.96%
- 295/35R20 vs 235/50R19+0.43%
- 295/35R20 vs 265/45R20+4.48%
- 295/35R20 vs 285/35R20-0.98%
Questions
Can I replace 295/35R20 with 305/40R20?
305/40R20 is outside the ±3% rule as a replacement for 295/35R20: the diameter differs by +5.25%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 295/35R20 and 305/40R20?
305/40R20 is 1.48" taller and 10 mm wider; the sidewall is +0.74". At an indicated 60 mph you'd actually be doing 63.1 mph.
Will 305/40R20 fit on 295/35R20 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.