285/70R18 vs 295/60R20

295/60R20 is 0.23 in (5.8 mm) taller than 285/70R18, a +0.68% diameter difference. With the speedometer set for 285/70R18, an indicated 60 mph is 60.4 mph on 295/60R20.

Is this a safe swap?

Diameter difference +0.68%: under 1%

By overall diameter alone, 295/60R20 is a near match for 285/70R18; 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.

285/70R18 vs 295/60R20 differences
Measurement	285/70R18	295/60R20	Difference	% diff
Overall diameter	33.71 in (856.2 mm)	33.94 in (862.0 mm)	+0.23 in (+5.8 mm)	+0.68%
Sidewall height	7.85 in (199.5 mm)	6.97 in (177.0 mm)	−0.89 in (−22.5 mm)	−11.28%
Section width	11.22 in (285.0 mm)	11.61 in (295.0 mm)	+0.39 in (+10.0 mm)	+3.51%
Circumference	105.90 in (2,689.8 mm)	106.62 in (2,708.1 mm)	+0.72 in (+18.2 mm)	+0.68%
Revolutions per mile	598	594	−4	−0.67%

True speed with the speedometer calibrated for 285/70R18
Indicated	Actual on 285/70R18	Actual on 295/60R20	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.4 mph	+0.4 mph
75 mph	75.0 mph	75.5 mph	+0.5 mph

Ride-height change: 295/60R20 raises the vehicle by 0.11 in (2.9 mm) at the axle (half the +5.8 mm diameter difference).

295/60R20 is 0.23 in taller than 285/70R18 and 10 mm wider, a 0.68% difference in overall diameter.

With the speedometer calibrated for 285/70R18, an indicated 60 mph is actually 60.4 mph on 295/60R20, and revolutions per mile change from 598 to 594.

295/60R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 285/70R18.

Size pages

Other comparisons with 285/70R18

Other comparisons with 295/60R20

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