195/45R17 vs 215/35R18

215/35R18 is 0.02 in (0.4 mm) taller than 195/45R17, a +0.07% diameter difference. With the speedometer set for 195/45R17, an indicated 60 mph is 60.0 mph on 215/35R18.

Is this a safe swap?

Diameter difference +0.07%: under 1%

By overall diameter alone, 215/35R18 is a near match for 195/45R17; 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.

195/45R17 vs 215/35R18 differences
Measurement	195/45R17	215/35R18	Difference	% diff
Overall diameter	23.91 in (607.3 mm)	23.93 in (607.7 mm)	+0.02 in (+0.4 mm)	+0.07%
Sidewall height	3.45 in (87.8 mm)	2.96 in (75.3 mm)	−0.49 in (−12.5 mm)	−14.25%
Section width	7.68 in (195.0 mm)	8.46 in (215.0 mm)	+0.79 in (+20.0 mm)	+10.26%
Circumference	75.11 in (1,907.9 mm)	75.16 in (1,909.1 mm)	+0.05 in (+1.3 mm)	+0.07%
Revolutions per mile	844	843	−1	−0.07%

True speed with the speedometer calibrated for 195/45R17
Indicated	Actual on 195/45R17	Actual on 215/35R18
30 mph	30.0 mph	30.0 mph
60 mph	60.0 mph	60.0 mph
75 mph	75.0 mph	75.0 mph

Ride-height change: 215/35R18 raises the vehicle by 0.01 in (0.2 mm) at the axle (half the +0.4 mm diameter difference).

215/35R18 is 0.02 in taller than 195/45R17 and 20 mm wider, a 0.07% difference in overall diameter.

With the speedometer calibrated for 195/45R17, an indicated 60 mph is actually 60.0 mph on 215/35R18, and revolutions per mile change from 844 to 843.

215/35R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 195/45R17.

Size pages

Other comparisons with 195/45R17

Other comparisons with 215/35R18

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