185/55R16 vs 205/55R16

205/55R16 is 0.87 in (22.0 mm) taller than 185/55R16, a +3.61% diameter difference. With the speedometer set for 185/55R16, an indicated 60 mph is 62.2 mph on 205/55R16.

Is this a safe swap?

Diameter difference +3.61%: outside the ±3% guideline

By overall diameter alone, 205/55R16 falls outside the ±3% range commonly used as a guideline when replacing 185/55R16; speedometer and ride-height changes are larger. 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 205/55R16 differences
Measurement	185/55R16	205/55R16	Difference	% diff
Overall diameter	24.01 in (609.9 mm)	24.88 in (631.9 mm)	+0.87 in (+22.0 mm)	+3.61%
Sidewall height	4.01 in (101.8 mm)	4.44 in (112.8 mm)	+0.43 in (+11.0 mm)	+10.81%
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)	78.16 in (1,985.2 mm)	+2.72 in (+69.1 mm)	+3.61%
Revolutions per mile	840	811	−29	−3.48%

True speed with the speedometer calibrated for 185/55R16
Indicated	Actual on 185/55R16	Actual on 205/55R16	Difference
30 mph	30.0 mph	31.1 mph	+1.1 mph
60 mph	60.0 mph	62.2 mph	+2.2 mph
75 mph	75.0 mph	77.7 mph	+2.7 mph

Ride-height change: 205/55R16 raises the vehicle by 0.43 in (11.0 mm) at the axle (half the +22.0 mm diameter difference).

205/55R16 is 0.87 in taller than 185/55R16 and 20 mm wider, a 3.61% difference in overall diameter.

With the speedometer calibrated for 185/55R16, an indicated 60 mph is actually 62.2 mph on 205/55R16, and revolutions per mile change from 840 to 811.

Both sizes mount on 16-inch wheels.

Size pages

Other comparisons with 185/55R16

Other comparisons with 205/55R16

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