245/55R20 vs 275/50R20

275/50R20 is 0.22 in (5.5 mm) taller than 245/55R20, a +0.71% diameter difference. With the speedometer set for 245/55R20, an indicated 60 mph is 60.4 mph on 275/50R20.

Is this a safe swap?

Diameter difference +0.71%: under 1%

By overall diameter alone, 275/50R20 is a near match for 245/55R20; 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.

245/55R20 vs 275/50R20 differences
Measurement	245/55R20	275/50R20	Difference	% diff
Overall diameter	30.61 in (777.5 mm)	30.83 in (783.0 mm)	+0.22 in (+5.5 mm)	+0.71%
Sidewall height	5.31 in (134.8 mm)	5.41 in (137.5 mm)	+0.11 in (+2.8 mm)	+2.04%
Section width	9.65 in (245.0 mm)	10.83 in (275.0 mm)	+1.18 in (+30.0 mm)	+12.24%
Circumference	96.16 in (2,442.6 mm)	96.85 in (2,459.9 mm)	+0.68 in (+17.3 mm)	+0.71%
Revolutions per mile	659	654	−5	−0.70%

True speed with the speedometer calibrated for 245/55R20
Indicated	Actual on 245/55R20	Actual on 275/50R20	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: 275/50R20 raises the vehicle by 0.11 in (2.8 mm) at the axle (half the +5.5 mm diameter difference).

275/50R20 is 0.22 in taller than 245/55R20 and 30 mm wider, a 0.71% difference in overall diameter.

With the speedometer calibrated for 245/55R20, an indicated 60 mph is actually 60.4 mph on 275/50R20, and revolutions per mile change from 659 to 654.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 245/55R20

Other comparisons with 275/50R20

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