165/65R14 vs 175/55R15

175/55R15 is 0.13 in (3.4 mm) taller than 165/65R14, a +0.60% diameter difference. With the speedometer set for 165/65R14, an indicated 60 mph is 60.4 mph on 175/55R15.

Is this a safe swap?

Diameter difference +0.60%: under 1%

By overall diameter alone, 175/55R15 is a near match for 165/65R14; the speedometer changes by less than 1%. 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.

165/65R14 vs 175/55R15 differences
Measurement	165/65R14	175/55R15	Difference	% diff
Overall diameter	22.44 in (570.1 mm)	22.58 in (573.5 mm)	+0.13 in (+3.4 mm)	+0.60%
Sidewall height	4.22 in (107.3 mm)	3.79 in (96.3 mm)	−0.43 in (−11.0 mm)	−10.26%
Section width	6.50 in (165.0 mm)	6.89 in (175.0 mm)	+0.39 in (+10.0 mm)	+6.06%
Circumference	70.51 in (1,791.0 mm)	70.93 in (1,801.7 mm)	+0.42 in (+10.7 mm)	+0.60%
Revolutions per mile	899	893	−5	−0.59%

True speed with the speedometer calibrated for 165/65R14
Indicated	Actual on 165/65R14	Actual on 175/55R15	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.4 mph	+0.4 mph
75 mph	75.0 mph	75.4 mph	+0.4 mph

Ride-height change: 175/55R15 raises the vehicle by 0.07 in (1.7 mm) at the axle (half the +3.4 mm diameter difference).

175/55R15 is 0.13 in taller than 165/65R14 and 10 mm wider, a 0.60% difference in overall diameter.

With the speedometer calibrated for 165/65R14, an indicated 60 mph is actually 60.4 mph on 175/55R15, and revolutions per mile change from 899 to 893.

175/55R15 mounts on a 15-inch wheel, a plus-1 fitment from the 14-inch wheel of 165/65R14.

Size pages

Other comparisons with 165/65R14

Other comparisons with 175/55R15

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