215/70R16 vs 285/45R18

285/45R18 is 0.25 in (6.3 mm) taller than 215/70R16, a +0.89% diameter difference. With the speedometer set for 215/70R16, an indicated 60 mph is 60.5 mph on 285/45R18.

Is this a safe swap?

Diameter difference +0.89%: under 1%

By overall diameter alone, 285/45R18 is a near match for 215/70R16; 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.

215/70R16 vs 285/45R18 differences
Measurement	215/70R16	285/45R18	Difference	% diff
Overall diameter	27.85 in (707.4 mm)	28.10 in (713.7 mm)	+0.25 in (+6.3 mm)	+0.89%
Sidewall height	5.93 in (150.5 mm)	5.05 in (128.3 mm)	−0.88 in (−22.2 mm)	−14.78%
Section width	8.46 in (215.0 mm)	11.22 in (285.0 mm)	+2.76 in (+70.0 mm)	+32.56%
Circumference	87.49 in (2,222.4 mm)	88.27 in (2,242.2 mm)	+0.78 in (+19.8 mm)	+0.89%
Revolutions per mile	724	718	−6	−0.88%

True speed with the speedometer calibrated for 215/70R16
Indicated	Actual on 215/70R16	Actual on 285/45R18	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.5 mph	+0.5 mph
75 mph	75.0 mph	75.7 mph	+0.7 mph

Ride-height change: 285/45R18 raises the vehicle by 0.12 in (3.2 mm) at the axle (half the +6.3 mm diameter difference).

285/45R18 is 0.25 in taller than 215/70R16 and 70 mm wider, a 0.89% difference in overall diameter.

With the speedometer calibrated for 215/70R16, an indicated 60 mph is actually 60.5 mph on 285/45R18, and revolutions per mile change from 724 to 718.

285/45R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 215/70R16.

Size pages

Other comparisons with 215/70R16

Other comparisons with 285/45R18

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