225/50R18 vs 295/30R20

295/30R20 is 0.11 in (2.8 mm) taller than 225/50R18, a +0.41% diameter difference. With the speedometer set for 225/50R18, an indicated 60 mph is 60.2 mph on 295/30R20.

Is this a safe swap?

Diameter difference +0.41%: under 1%

By overall diameter alone, 295/30R20 is a near match for 225/50R18; 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.

225/50R18 vs 295/30R20 differences
Measurement	225/50R18	295/30R20	Difference	% diff
Overall diameter	26.86 in (682.2 mm)	26.97 in (685.0 mm)	+0.11 in (+2.8 mm)	+0.41%
Sidewall height	4.43 in (112.5 mm)	3.48 in (88.5 mm)	−0.94 in (−24.0 mm)	−21.33%
Section width	8.86 in (225.0 mm)	11.61 in (295.0 mm)	+2.76 in (+70.0 mm)	+31.11%
Circumference	84.38 in (2,143.2 mm)	84.72 in (2,152.0 mm)	+0.35 in (+8.8 mm)	+0.41%
Revolutions per mile	751	748	−3	−0.41%

True speed with the speedometer calibrated for 225/50R18
Indicated	Actual on 225/50R18	Actual on 295/30R20	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	75.3 mph	+0.3 mph

Ride-height change: 295/30R20 raises the vehicle by 0.06 in (1.4 mm) at the axle (half the +2.8 mm diameter difference).

295/30R20 is 0.11 in taller than 225/50R18 and 70 mm wider, a 0.41% difference in overall diameter.

With the speedometer calibrated for 225/50R18, an indicated 60 mph is actually 60.2 mph on 295/30R20, and revolutions per mile change from 751 to 748.

295/30R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 225/50R18.

Size pages

Other comparisons with 225/50R18

Other comparisons with 295/30R20

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