205/50R16 vs 215/35R18

215/35R18 is 0.15 in (3.7 mm) shorter than 205/50R16, a −0.61% diameter difference. With the speedometer set for 205/50R16, an indicated 60 mph is 59.6 mph on 215/35R18.

Is this a safe swap?

Diameter difference −0.61%: under 1%

By overall diameter alone, 215/35R18 is a near match for 205/50R16; 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.

205/50R16 vs 215/35R18 differences
Measurement	205/50R16	215/35R18	Difference	% diff
Overall diameter	24.07 in (611.4 mm)	23.93 in (607.7 mm)	−0.15 in (−3.7 mm)	−0.61%
Sidewall height	4.04 in (102.5 mm)	2.96 in (75.3 mm)	−1.07 in (−27.2 mm)	−26.59%
Section width	8.07 in (205.0 mm)	8.46 in (215.0 mm)	+0.39 in (+10.0 mm)	+4.88%
Circumference	75.62 in (1,920.8 mm)	75.16 in (1,909.1 mm)	−0.46 in (−11.6 mm)	−0.61%
Revolutions per mile	838	843	+5	+0.61%

True speed with the speedometer calibrated for 205/50R16
Indicated	Actual on 205/50R16	Actual on 215/35R18	Difference
30 mph	30.0 mph	29.8 mph	−0.2 mph
60 mph	60.0 mph	59.6 mph	−0.4 mph
75 mph	75.0 mph	74.5 mph	−0.5 mph

Ride-height change: 215/35R18 lowers the vehicle by 0.07 in (1.8 mm) at the axle (half the −3.7 mm diameter difference).

215/35R18 is 0.15 in shorter than 205/50R16 and 10 mm wider, a 0.61% difference in overall diameter.

With the speedometer calibrated for 205/50R16, an indicated 60 mph is actually 59.6 mph on 215/35R18, and revolutions per mile change from 838 to 843.

215/35R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 205/50R16.

Size pages

Other comparisons with 205/50R16

Other comparisons with 215/35R18

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