TireSizesFinder

155/80R13 vs 185/55R15

185/55R15 is 0.25 in (6.3 mm) taller than 155/80R13, a +1.09% diameter difference. With the speedometer set for 155/80R13, an indicated 60 mph is 60.7 mph on 185/55R15.

Is this a safe swap?

Diameter difference +1.09%: within the ±3% guideline

By overall diameter alone, 185/55R15 falls inside the ±3% range commonly used as a guideline when replacing 155/80R13. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 155/80R13 (22.76 in) vs 185/55R15 (23.01 in)155/80R1322.76 in × 6.10 in185/55R1523.01 in × 7.28 in
Side profile and tread width, drawn to the same scale.
155/80R13 vs 185/55R15 differences
Measurement155/80R13185/55R15Difference% diff
Overall diameter22.76 in (578.2 mm)23.01 in (584.5 mm)+0.25 in (+6.3 mm)+1.09%
Sidewall height4.88 in (124.0 mm)4.01 in (101.8 mm)−0.88 in (−22.2 mm)−17.94%
Section width6.10 in (155.0 mm)7.28 in (185.0 mm)+1.18 in (+30.0 mm)+19.35%
Circumference71.51 in (1,816.5 mm)72.29 in (1,836.3 mm)+0.78 in (+19.8 mm)+1.09%
Revolutions per mile886876−10−1.08%
True speed with the speedometer calibrated for 155/80R13
IndicatedActual on 155/80R13Actual on 185/55R15Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.7 mph+0.7 mph
75 mph75.0 mph75.8 mph+0.8 mph

Ride-height change: 185/55R15 raises the vehicle by 0.12 in (3.1 mm) at the axle (half the +6.3 mm diameter difference).

185/55R15 is 0.25 in taller than 155/80R13 and 30 mm wider, a 1.09% difference in overall diameter.

With the speedometer calibrated for 155/80R13, an indicated 60 mph is actually 60.7 mph on 185/55R15, and revolutions per mile change from 886 to 876.

185/55R15 mounts on a 15-inch wheel, a plus-2 fitment from the 13-inch wheel of 155/80R13.

Size pages

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