175/80R13 vs 185/65R15

185/65R15 is 0.44 in (11.3 mm) taller than 175/80R13, a +1.85% diameter difference. With the speedometer set for 175/80R13, an indicated 60 mph is 61.1 mph on 185/65R15.

Is this a safe swap?

Diameter difference +1.85%: within the ±3% guideline

By overall diameter alone, 185/65R15 falls inside the ±3% range commonly used as a guideline when replacing 175/80R13. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

175/80R13 vs 185/65R15 differences
Measurement	175/80R13	185/65R15	Difference	% diff
Overall diameter	24.02 in (610.2 mm)	24.47 in (621.5 mm)	+0.44 in (+11.3 mm)	+1.85%
Sidewall height	5.51 in (140.0 mm)	4.73 in (120.3 mm)	−0.78 in (−19.7 mm)	−14.11%
Section width	6.89 in (175.0 mm)	7.28 in (185.0 mm)	+0.39 in (+10.0 mm)	+5.71%
Circumference	75.47 in (1,917.0 mm)	76.87 in (1,952.5 mm)	+1.40 in (+35.5 mm)	+1.85%
Revolutions per mile	840	824	−15	−1.82%

True speed with the speedometer calibrated for 175/80R13
Indicated	Actual on 175/80R13	Actual on 185/65R15	Difference
30 mph	30.0 mph	30.6 mph	+0.6 mph
60 mph	60.0 mph	61.1 mph	+1.1 mph
75 mph	75.0 mph	76.4 mph	+1.4 mph

Ride-height change: 185/65R15 raises the vehicle by 0.22 in (5.6 mm) at the axle (half the +11.3 mm diameter difference).

185/65R15 is 0.44 in taller than 175/80R13 and 10 mm wider, a 1.85% difference in overall diameter.

With the speedometer calibrated for 175/80R13, an indicated 60 mph is actually 61.1 mph on 185/65R15, and revolutions per mile change from 840 to 824.

185/65R15 mounts on a 15-inch wheel, a plus-2 fitment from the 13-inch wheel of 175/80R13.

Size pages

Other comparisons with 175/80R13

Other comparisons with 185/65R15

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.