295/35R21 vs 295/40R21
295/40R21 is outside the ±3% rule as a replacement for 295/35R21: the diameter differs by +3.99%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 295/40R21 on a car calibrated for 295/35R21, 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 295/35R21
- 295/35R21 vs 255/45R20-0.32%
- 295/35R21 vs 265/45R20+0.89%
- 295/35R21 vs 265/40R21+0.74%
- 295/35R21 vs 275/35R21-1.89%
- 295/35R21 vs 255/40R21-0.34%
- 295/35R21 vs 265/35R21-2.84%
- 295/35R21 vs 265/35R22+0.59%
- 295/35R21 vs 295/40R20+0.55%
- 295/35R21 vs 245/35R21-4.73%
- 295/35R21 vs 285/40R21+2.91%
- 295/35R21 vs 265/45R21+4.32%
- 295/35R21 vs 285/40R20-0.53%
Questions
Can I replace 295/35R21 with 295/40R21?
295/40R21 is outside the ±3% rule as a replacement for 295/35R21: the diameter differs by +3.99%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 295/35R21 and 295/40R21?
295/40R21 is 1.16" taller and 0 mm wider; the sidewall is +0.58". At an indicated 60 mph you'd actually be doing 62.4 mph.
Will 295/40R21 fit on 295/35R21 wheels?
Both use a 21" rim, so the wheel diameter matches; check the wheel's width range for a 295 mm tire and the fender clearance.