185/55R16 vs 205/50R16

205/50R16 is 0.06 in (1.5 mm) taller than 185/55R16, a +0.25% diameter difference. With the speedometer set for 185/55R16, an indicated 60 mph is 60.1 mph on 205/50R16.

Is this a safe swap?

Diameter difference +0.25%: under 1%

By overall diameter alone, 205/50R16 is a near match for 185/55R16; 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.

185/55R16 vs 205/50R16 differences
Measurement	185/55R16	205/50R16	Difference	% diff
Overall diameter	24.01 in (609.9 mm)	24.07 in (611.4 mm)	+0.06 in (+1.5 mm)	+0.25%
Sidewall height	4.01 in (101.8 mm)	4.04 in (102.5 mm)	+0.03 in (+0.8 mm)	+0.74%
Section width	7.28 in (185.0 mm)	8.07 in (205.0 mm)	+0.79 in (+20.0 mm)	+10.81%
Circumference	75.44 in (1,916.1 mm)	75.62 in (1,920.8 mm)	+0.19 in (+4.7 mm)	+0.25%
Revolutions per mile	840	838	−2	−0.25%

True speed with the speedometer calibrated for 185/55R16
Indicated	Actual on 185/55R16	Actual on 205/50R16	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.1 mph	+0.1 mph
75 mph	75.0 mph	75.2 mph	+0.2 mph

Ride-height change: 205/50R16 raises the vehicle by 0.03 in (0.8 mm) at the axle (half the +1.5 mm diameter difference).

205/50R16 is 0.06 in taller than 185/55R16 and 20 mm wider, a 0.25% difference in overall diameter.

With the speedometer calibrated for 185/55R16, an indicated 60 mph is actually 60.1 mph on 205/50R16, and revolutions per mile change from 840 to 838.

Both sizes mount on 16-inch wheels.

Size pages

Other comparisons with 185/55R16

Other comparisons with 205/50R16

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