225/50R15 vs 185/65R15
185/65R15 is a safe swap for 225/50R15 by the usual ±3% rule: the diameter differs by +2.56%.
Speedometer and odometer
With 185/65R15 on a car calibrated for 225/50R15, the speedometer reads 58.5 mph when you're really doing 60, and the odometer under-counts by 2.6%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.8 mph |
| 45 mph | 46.2 mph |
| 60 mph | 61.5 mph |
| 70 mph | 71.8 mph |
| 80 mph | 82.0 mph |
Other sizes close to 225/50R15
- 225/50R15 vs 195/65R15+4.70%
- 225/50R15 vs 185/60R15-0.50%
- 225/50R15 vs 195/60R15+1.49%
- 225/50R15 vs 205/50R16+0.89%
- 225/50R15 vs 175/65R15+0.41%
- 225/50R15 vs 205/50R15-3.30%
- 225/50R15 vs 195/50R16-0.76%
- 225/50R15 vs 195/55R15-1.73%
- 225/50R15 vs 205/60R15+3.47%
- 225/50R15 vs 185/55R15-3.55%
- 225/50R15 vs 185/55R16+0.64%
- 225/50R15 vs 175/70R14-0.89%
Questions
Can I replace 225/50R15 with 185/65R15?
185/65R15 is a safe swap for 225/50R15 by the usual ±3% rule: the diameter differs by +2.56%.
What's the difference between 225/50R15 and 185/65R15?
185/65R15 is 0.61" taller and 40 mm narrower; the sidewall is +0.31". At an indicated 60 mph you'd actually be doing 61.5 mph.
Will 185/65R15 fit on 225/50R15 wheels?
Both use a 15" rim, so the wheel diameter matches; check the wheel's width range for a 185 mm tire and the fender clearance.