235/80R17 vs 305/65R17
305/65R17 is a safe swap for 235/80R17 by the usual ±3% rule: the diameter differs by +2.54%.
Speedometer and odometer
With 305/65R17 on a car calibrated for 235/80R17, the speedometer reads 58.5 mph when you're really doing 60, and the odometer under-counts by 2.5%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.8 mph |
| 45 mph | 46.1 mph |
| 60 mph | 61.5 mph |
| 70 mph | 71.8 mph |
| 80 mph | 82.0 mph |
Other sizes close to 235/80R17
- 235/80R17 vs 265/70R17-0.62%
- 235/80R17 vs 275/65R18+0.85%
- 235/80R17 vs 265/75R16-0.48%
- 235/80R17 vs 245/70R17-4.09%
- 235/80R17 vs 285/70R17+2.85%
- 235/80R17 vs 265/65R18-0.76%
- 235/80R17 vs 245/75R17-1.05%
- 235/80R17 vs 265/65R17-3.90%
- 235/80R17 vs 235/85R16-0.24%
- 235/80R17 vs 255/70R18+0.79%
- 235/80R17 vs 255/70R17-2.35%
- 235/80R17 vs 255/75R17+0.80%
Questions
Can I replace 235/80R17 with 305/65R17?
305/65R17 is a safe swap for 235/80R17 by the usual ±3% rule: the diameter differs by +2.54%.
What's the difference between 235/80R17 and 305/65R17?
305/65R17 is 0.81" taller and 70 mm wider; the sidewall is +0.40". At an indicated 60 mph you'd actually be doing 61.5 mph.
Will 305/65R17 fit on 235/80R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 305 mm tire and the fender clearance.