295/35R18 vs 225/35R20

225/35R20 is 0.07 in (1.8 mm) taller than 295/35R18, a +0.27% diameter difference. With the speedometer set for 295/35R18, an indicated 60 mph is 60.2 mph on 225/35R20.

Is this a safe swap?

Diameter difference +0.27%: under 1%

By overall diameter alone, 225/35R20 is a near match for 295/35R18; 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.

295/35R18 vs 225/35R20 differences
Measurement	295/35R18	225/35R20	Difference	% diff
Overall diameter	26.13 in (663.7 mm)	26.20 in (665.5 mm)	+0.07 in (+1.8 mm)	+0.27%
Sidewall height	4.06 in (103.3 mm)	3.10 in (78.8 mm)	−0.96 in (−24.5 mm)	−23.73%
Section width	11.61 in (295.0 mm)	8.86 in (225.0 mm)	−2.76 in (−70.0 mm)	−23.73%
Circumference	82.09 in (2,085.1 mm)	82.31 in (2,090.7 mm)	+0.22 in (+5.7 mm)	+0.27%
Revolutions per mile	772	770	−2	−0.27%

True speed with the speedometer calibrated for 295/35R18
Indicated	Actual on 295/35R18	Actual on 225/35R20	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.2 mph	+0.2 mph
75 mph	75.0 mph	75.2 mph	+0.2 mph

Ride-height change: 225/35R20 raises the vehicle by 0.04 in (0.9 mm) at the axle (half the +1.8 mm diameter difference).

225/35R20 is 0.07 in taller than 295/35R18 and 70 mm narrower, a 0.27% difference in overall diameter.

With the speedometer calibrated for 295/35R18, an indicated 60 mph is actually 60.2 mph on 225/35R20, and revolutions per mile change from 772 to 770.

225/35R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 295/35R18.

Size pages

Other comparisons with 295/35R18

Other comparisons with 225/35R20

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