295/45R20 vs 245/55R20

245/55R20 is 0.16 in (4.0 mm) taller than 295/45R20, a +0.52% diameter difference. With the speedometer set for 295/45R20, an indicated 60 mph is 60.3 mph on 245/55R20.

Is this a safe swap?

Diameter difference +0.52%: under 1%

By overall diameter alone, 245/55R20 is a near match for 295/45R20; 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.

295/45R20 vs 245/55R20 differences
Measurement	295/45R20	245/55R20	Difference	% diff
Overall diameter	30.45 in (773.5 mm)	30.61 in (777.5 mm)	+0.16 in (+4.0 mm)	+0.52%
Sidewall height	5.23 in (132.8 mm)	5.31 in (134.8 mm)	+0.08 in (+2.0 mm)	+1.51%
Section width	11.61 in (295.0 mm)	9.65 in (245.0 mm)	−1.97 in (−50.0 mm)	−16.95%
Circumference	95.67 in (2,430.0 mm)	96.16 in (2,442.6 mm)	+0.49 in (+12.6 mm)	+0.52%
Revolutions per mile	662	659	−3	−0.51%

True speed with the speedometer calibrated for 295/45R20
Indicated	Actual on 295/45R20	Actual on 245/55R20	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.3 mph	+0.3 mph
75 mph	75.0 mph	75.4 mph	+0.4 mph

Ride-height change: 245/55R20 raises the vehicle by 0.08 in (2.0 mm) at the axle (half the +4.0 mm diameter difference).

245/55R20 is 0.16 in taller than 295/45R20 and 50 mm narrower, a 0.52% difference in overall diameter.

With the speedometer calibrated for 295/45R20, an indicated 60 mph is actually 60.3 mph on 245/55R20, and revolutions per mile change from 662 to 659.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 295/45R20

Other comparisons with 245/55R20

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