TireSizesFinder

185/70R14 vs 225/50R15

225/50R15 is 0.34 in (8.6 mm) shorter than 185/70R14, a −1.40% diameter difference. With the speedometer set for 185/70R14, an indicated 60 mph is 59.2 mph on 225/50R15.

Is this a safe swap?

Diameter difference −1.40%: within the ±3% guideline

By overall diameter alone, 225/50R15 falls inside the ±3% range commonly used as a guideline when replacing 185/70R14. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 185/70R14 (24.20 in) vs 225/50R15 (23.86 in)185/70R1424.20 in × 7.28 in225/50R1523.86 in × 8.86 in
Side profile and tread width, drawn to the same scale.
185/70R14 vs 225/50R15 differences
Measurement185/70R14225/50R15Difference% diff
Overall diameter24.20 in (614.6 mm)23.86 in (606.0 mm)−0.34 in (−8.6 mm)−1.40%
Sidewall height5.10 in (129.5 mm)4.43 in (112.5 mm)−0.67 in (−17.0 mm)−13.13%
Section width7.28 in (185.0 mm)8.86 in (225.0 mm)+1.57 in (+40.0 mm)+21.62%
Circumference76.02 in (1,930.8 mm)74.95 in (1,903.8 mm)−1.06 in (−27.0 mm)−1.40%
Revolutions per mile834845+12+1.42%
True speed with the speedometer calibrated for 185/70R14
IndicatedActual on 185/70R14Actual on 225/50R15Difference
30 mph30.0 mph29.6 mph−0.4 mph
60 mph60.0 mph59.2 mph−0.8 mph
75 mph75.0 mph74.0 mph−1.0 mph

Ride-height change: 225/50R15 lowers the vehicle by 0.17 in (4.3 mm) at the axle (half the −8.6 mm diameter difference).

225/50R15 is 0.34 in shorter than 185/70R14 and 40 mm wider, a 1.40% difference in overall diameter.

With the speedometer calibrated for 185/70R14, an indicated 60 mph is actually 59.2 mph on 225/50R15, and revolutions per mile change from 834 to 845.

225/50R15 mounts on a 15-inch wheel, a plus-1 fitment from the 14-inch wheel of 185/70R14.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.