TireSizesFinder

175/70R13 vs 185/55R15

185/55R15 is 0.37 in (9.3 mm) taller than 175/70R13, a +1.62% diameter difference. With the speedometer set for 175/70R13, an indicated 60 mph is 61.0 mph on 185/55R15.

Is this a safe swap?

Diameter difference +1.62%: within the ±3% guideline

By overall diameter alone, 185/55R15 falls inside the ±3% range commonly used as a guideline when replacing 175/70R13. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 175/70R13 (22.65 in) vs 185/55R15 (23.01 in)175/70R1322.65 in × 6.89 in185/55R1523.01 in × 7.28 in
Side profile and tread width, drawn to the same scale.
175/70R13 vs 185/55R15 differences
Measurement175/70R13185/55R15Difference% diff
Overall diameter22.65 in (575.2 mm)23.01 in (584.5 mm)+0.37 in (+9.3 mm)+1.62%
Sidewall height4.82 in (122.5 mm)4.01 in (101.8 mm)−0.82 in (−20.7 mm)−16.94%
Section width6.89 in (175.0 mm)7.28 in (185.0 mm)+0.39 in (+10.0 mm)+5.71%
Circumference71.14 in (1,807.0 mm)72.29 in (1,836.3 mm)+1.15 in (+29.2 mm)+1.62%
Revolutions per mile891876−14−1.59%
True speed with the speedometer calibrated for 175/70R13
IndicatedActual on 175/70R13Actual on 185/55R15Difference
30 mph30.0 mph30.5 mph+0.5 mph
60 mph60.0 mph61.0 mph+1.0 mph
75 mph75.0 mph76.2 mph+1.2 mph

Ride-height change: 185/55R15 raises the vehicle by 0.18 in (4.6 mm) at the axle (half the +9.3 mm diameter difference).

185/55R15 is 0.37 in taller than 175/70R13 and 10 mm wider, a 1.62% difference in overall diameter.

With the speedometer calibrated for 175/70R13, an indicated 60 mph is actually 61.0 mph on 185/55R15, and revolutions per mile change from 891 to 876.

185/55R15 mounts on a 15-inch wheel, a plus-2 fitment from the 13-inch wheel of 175/70R13.

Size pages

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