285/45R18 vs 295/35R20

295/35R20 is 0.03 in (0.8 mm) taller than 285/45R18, a +0.11% diameter difference. With the speedometer set for 285/45R18, an indicated 60 mph is 60.1 mph on 295/35R20.

Is this a safe swap?

Diameter difference +0.11%: under 1%

By overall diameter alone, 295/35R20 is a near match for 285/45R18; 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.

285/45R18 vs 295/35R20 differences
Measurement	285/45R18	295/35R20	Difference	% diff
Overall diameter	28.10 in (713.7 mm)	28.13 in (714.5 mm)	+0.03 in (+0.8 mm)	+0.11%
Sidewall height	5.05 in (128.3 mm)	4.06 in (103.3 mm)	−0.98 in (−25.0 mm)	−19.49%
Section width	11.22 in (285.0 mm)	11.61 in (295.0 mm)	+0.39 in (+10.0 mm)	+3.51%
Circumference	88.27 in (2,242.2 mm)	88.37 in (2,244.7 mm)	+0.10 in (+2.5 mm)	+0.11%
Revolutions per mile	718	717	−1	−0.11%

True speed with the speedometer calibrated for 285/45R18
Indicated	Actual on 285/45R18	Actual on 295/35R20	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: 295/35R20 raises the vehicle by 0.02 in (0.4 mm) at the axle (half the +0.8 mm diameter difference).

295/35R20 is 0.03 in taller than 285/45R18 and 10 mm wider, a 0.11% difference in overall diameter.

With the speedometer calibrated for 285/45R18, an indicated 60 mph is actually 60.1 mph on 295/35R20, and revolutions per mile change from 718 to 717.

295/35R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 285/45R18.

Size pages

Other comparisons with 285/45R18

Other comparisons with 295/35R20

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