TireSizesFinder

185/70R14 vs 205/55R15

205/55R15 is 0.32 in (8.1 mm) shorter than 185/70R14, a −1.32% diameter difference. With the speedometer set for 185/70R14, an indicated 60 mph is 59.2 mph on 205/55R15.

Is this a safe swap?

Diameter difference −1.32%: within the ±3% guideline

By overall diameter alone, 205/55R15 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 205/55R15 (23.88 in)185/70R1424.20 in × 7.28 in205/55R1523.88 in × 8.07 in
Side profile and tread width, drawn to the same scale.
185/70R14 vs 205/55R15 differences
Measurement185/70R14205/55R15Difference% diff
Overall diameter24.20 in (614.6 mm)23.88 in (606.5 mm)−0.32 in (−8.1 mm)−1.32%
Sidewall height5.10 in (129.5 mm)4.44 in (112.8 mm)−0.66 in (−16.7 mm)−12.93%
Section width7.28 in (185.0 mm)8.07 in (205.0 mm)+0.79 in (+20.0 mm)+10.81%
Circumference76.02 in (1,930.8 mm)75.01 in (1,905.4 mm)−1.00 in (−25.4 mm)−1.32%
Revolutions per mile834845+11+1.34%
True speed with the speedometer calibrated for 185/70R14
IndicatedActual on 185/70R14Actual on 205/55R15Difference
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: 205/55R15 lowers the vehicle by 0.16 in (4.0 mm) at the axle (half the −8.1 mm diameter difference).

205/55R15 is 0.32 in shorter than 185/70R14 and 20 mm wider, a 1.32% difference in overall diameter.

With the speedometer calibrated for 185/70R14, an indicated 60 mph is actually 59.2 mph on 205/55R15, and revolutions per mile change from 834 to 845.

205/55R15 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.