185/55R16 vs 225/50R16
225/50R16 is outside the ±3% rule as a replacement for 185/55R16: the diameter differs by +3.53%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 225/50R16 on a car calibrated for 185/55R16, the speedometer reads 58.0 mph when you're really doing 60, and the odometer under-counts by 3.5%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.1 mph |
| 45 mph | 46.6 mph |
| 60 mph | 62.1 mph |
| 70 mph | 72.5 mph |
| 80 mph | 82.8 mph |
Other sizes close to 185/55R16
Questions
Can I replace 185/55R16 with 225/50R16?
225/50R16 is outside the ±3% rule as a replacement for 185/55R16: the diameter differs by +3.53%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 185/55R16 and 225/50R16?
225/50R16 is 0.85" taller and 40 mm wider; the sidewall is +0.42". At an indicated 60 mph you'd actually be doing 62.1 mph.
Will 225/50R16 fit on 185/55R16 wheels?
Both use a 16" rim, so the wheel diameter matches; check the wheel's width range for a 225 mm tire and the fender clearance.