165/70R14 vs 205/50R15

205/50R15 is 0.02 in (0.6 mm) shorter than 165/70R14, a −0.10% diameter difference. With the speedometer set for 165/70R14, an indicated 60 mph is 59.9 mph on 205/50R15.

Is this a safe swap?

Diameter difference −0.10%: under 1%

By overall diameter alone, 205/50R15 is a near match for 165/70R14; 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.

165/70R14 vs 205/50R15 differences
Measurement	165/70R14	205/50R15	Difference	% diff
Overall diameter	23.09 in (586.6 mm)	23.07 in (586.0 mm)	−0.02 in (−0.6 mm)	−0.10%
Sidewall height	4.55 in (115.5 mm)	4.04 in (102.5 mm)	−0.51 in (−13.0 mm)	−11.26%
Section width	6.50 in (165.0 mm)	8.07 in (205.0 mm)	+1.57 in (+40.0 mm)	+24.24%
Circumference	72.55 in (1,842.9 mm)	72.48 in (1,841.0 mm)	−0.07 in (−1.9 mm)	−0.10%
Revolutions per mile	873	874	+1	+0.10%

True speed with the speedometer calibrated for 165/70R14
Indicated	Actual on 165/70R14	Actual on 205/50R15	Difference
30 mph	30.0 mph	30.0 mph	0.0 mph
60 mph	60.0 mph	59.9 mph	−0.1 mph
75 mph	75.0 mph	74.9 mph	−0.1 mph

Ride-height change: 205/50R15 lowers the vehicle by 0.01 in (0.3 mm) at the axle (half the −0.6 mm diameter difference).

205/50R15 is 0.02 in shorter than 165/70R14 and 40 mm wider, a 0.10% difference in overall diameter.

With the speedometer calibrated for 165/70R14, an indicated 60 mph is actually 59.9 mph on 205/50R15, and revolutions per mile change from 873 to 874.

205/50R15 mounts on a 15-inch wheel, a plus-1 fitment from the 14-inch wheel of 165/70R14.

Size pages

Other comparisons with 165/70R14

Other comparisons with 205/50R15

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