295/35R20 vs 305/30R21
305/30R21 is a safe swap for 295/35R20 by the usual ±3% rule: the diameter differs by +0.27%.
Speedometer and odometer
With 305/30R21 on a car calibrated for 295/35R20, the speedometer reads 59.8 mph when you're really doing 60, and the odometer under-counts by 0.3%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.2 mph |
| 70 mph | 70.2 mph |
| 80 mph | 80.2 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 305/30R21?
305/30R21 is a safe swap for 295/35R20 by the usual ±3% rule: the diameter differs by +0.27%.
What's the difference between 295/35R20 and 305/30R21?
305/30R21 is 0.07" taller and 10 mm wider; the sidewall is -0.46". At an indicated 60 mph you'd actually be doing 60.2 mph.
Will 305/30R21 fit on 295/35R20 wheels?
No — 295/35R20 needs a 20" wheel and 305/30R21 a 21" wheel. This is a plus/minus-size swap that changes wheels too.