195/55R16 vs 235/35R18

235/35R18 is 0.03 in (0.8 mm) taller than 195/55R16, a +0.13% diameter difference. With the speedometer set for 195/55R16, an indicated 60 mph is 60.1 mph on 235/35R18.

Is this a safe swap?

Diameter difference +0.13%: under 1%

By overall diameter alone, 235/35R18 is a near match for 195/55R16; 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.

195/55R16 vs 235/35R18 differences
Measurement	195/55R16	235/35R18	Difference	% diff
Overall diameter	24.44 in (620.9 mm)	24.48 in (621.7 mm)	+0.03 in (+0.8 mm)	+0.13%
Sidewall height	4.22 in (107.3 mm)	3.24 in (82.3 mm)	−0.98 in (−25.0 mm)	−23.31%
Section width	7.68 in (195.0 mm)	9.25 in (235.0 mm)	+1.57 in (+40.0 mm)	+20.51%
Circumference	76.80 in (1,950.6 mm)	76.89 in (1,953.1 mm)	+0.10 in (+2.5 mm)	+0.13%
Revolutions per mile	825	824	−1	−0.13%

True speed with the speedometer calibrated for 195/55R16
Indicated	Actual on 195/55R16	Actual on 235/35R18	Difference
30 mph	30.0 mph	30.0 mph	0.0 mph
60 mph	60.0 mph	60.1 mph	+0.1 mph
75 mph	75.0 mph	75.1 mph	+0.1 mph

Ride-height change: 235/35R18 raises the vehicle by 0.02 in (0.4 mm) at the axle (half the +0.8 mm diameter difference).

235/35R18 is 0.03 in taller than 195/55R16 and 40 mm wider, a 0.13% difference in overall diameter.

With the speedometer calibrated for 195/55R16, an indicated 60 mph is actually 60.1 mph on 235/35R18, and revolutions per mile change from 825 to 824.

235/35R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 195/55R16.

Size pages

Other comparisons with 195/55R16

Other comparisons with 235/35R18

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