TireSizesFinder

225/50R15 vs 185/55R16

185/55R16 is 0.15 in (3.9 mm) taller than 225/50R15, a +0.64% diameter difference. With the speedometer set for 225/50R15, an indicated 60 mph is 60.4 mph on 185/55R16.

Is this a safe swap?

Diameter difference +0.64%: under 1%

By overall diameter alone, 185/55R16 is a near match for 225/50R15; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 225/50R15 (23.86 in) vs 185/55R16 (24.01 in)225/50R1523.86 in × 8.86 in185/55R1624.01 in × 7.28 in
Side profile and tread width, drawn to the same scale.
225/50R15 vs 185/55R16 differences
Measurement225/50R15185/55R16Difference% diff
Overall diameter23.86 in (606.0 mm)24.01 in (609.9 mm)+0.15 in (+3.9 mm)+0.64%
Sidewall height4.43 in (112.5 mm)4.01 in (101.8 mm)−0.42 in (−10.7 mm)−9.56%
Section width8.86 in (225.0 mm)7.28 in (185.0 mm)−1.57 in (−40.0 mm)−17.78%
Circumference74.95 in (1,903.8 mm)75.44 in (1,916.1 mm)+0.48 in (+12.3 mm)+0.64%
Revolutions per mile845840−5−0.64%
True speed with the speedometer calibrated for 225/50R15
IndicatedActual on 225/50R15Actual on 185/55R16Difference
30 mph30.0 mph30.2 mph+0.2 mph
60 mph60.0 mph60.4 mph+0.4 mph
75 mph75.0 mph75.5 mph+0.5 mph

Ride-height change: 185/55R16 raises the vehicle by 0.08 in (1.9 mm) at the axle (half the +3.9 mm diameter difference).

185/55R16 is 0.15 in taller than 225/50R15 and 40 mm narrower, a 0.64% difference in overall diameter.

With the speedometer calibrated for 225/50R15, an indicated 60 mph is actually 60.4 mph on 185/55R16, and revolutions per mile change from 845 to 840.

185/55R16 mounts on a 16-inch wheel, a plus-1 fitment from the 15-inch wheel of 225/50R15.

Size pages

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