225/55R16 vs 285/35R18

285/35R18 is 0.11 in (2.8 mm) taller than 225/55R16, a +0.43% diameter difference. With the speedometer set for 225/55R16, an indicated 60 mph is 60.3 mph on 285/35R18.

Is this a safe swap?

Diameter difference +0.43%: under 1%

By overall diameter alone, 285/35R18 is a near match for 225/55R16; 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.

225/55R16 vs 285/35R18 differences
Measurement	225/55R16	285/35R18	Difference	% diff
Overall diameter	25.74 in (653.9 mm)	25.85 in (656.7 mm)	+0.11 in (+2.8 mm)	+0.43%
Sidewall height	4.87 in (123.8 mm)	3.93 in (99.8 mm)	−0.94 in (−24.0 mm)	−19.39%
Section width	8.86 in (225.0 mm)	11.22 in (285.0 mm)	+2.36 in (+60.0 mm)	+26.67%
Circumference	80.88 in (2,054.3 mm)	81.22 in (2,063.1 mm)	+0.35 in (+8.8 mm)	+0.43%
Revolutions per mile	783	780	−3	−0.43%

True speed with the speedometer calibrated for 225/55R16
Indicated	Actual on 225/55R16	Actual on 285/35R18	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.3 mph	+0.3 mph
75 mph	75.0 mph	75.3 mph	+0.3 mph

Ride-height change: 285/35R18 raises the vehicle by 0.06 in (1.4 mm) at the axle (half the +2.8 mm diameter difference).

285/35R18 is 0.11 in taller than 225/55R16 and 60 mm wider, a 0.43% difference in overall diameter.

With the speedometer calibrated for 225/55R16, an indicated 60 mph is actually 60.3 mph on 285/35R18, and revolutions per mile change from 783 to 780.

285/35R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 225/55R16.

Size pages

Other comparisons with 225/55R16

Other comparisons with 285/35R18

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