TireSizesFinder

275/55R19 vs 245/55R20

245/55R20 is 0.30 in (7.6 mm) shorter than 275/55R19, a −0.97% diameter difference. With the speedometer set for 275/55R19, an indicated 60 mph is 59.4 mph on 245/55R20.

Is this a safe swap?

Diameter difference −0.97%: under 1%

By overall diameter alone, 245/55R20 is a near match for 275/55R19; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 275/55R19 (30.91 in) vs 245/55R20 (30.61 in)275/55R1930.91 in × 10.83 in245/55R2030.61 in × 9.65 in
Side profile and tread width, drawn to the same scale.
275/55R19 vs 245/55R20 differences
Measurement275/55R19245/55R20Difference% diff
Overall diameter30.91 in (785.1 mm)30.61 in (777.5 mm)−0.30 in (−7.6 mm)−0.97%
Sidewall height5.95 in (151.3 mm)5.31 in (134.8 mm)−0.65 in (−16.5 mm)−10.91%
Section width10.83 in (275.0 mm)9.65 in (245.0 mm)−1.18 in (−30.0 mm)−10.91%
Circumference97.10 in (2,466.5 mm)96.16 in (2,442.6 mm)−0.94 in (−23.9 mm)−0.97%
Revolutions per mile652659+6+0.98%
True speed with the speedometer calibrated for 275/55R19
IndicatedActual on 275/55R19Actual on 245/55R20Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.4 mph−0.6 mph
75 mph75.0 mph74.3 mph−0.7 mph

Ride-height change: 245/55R20 lowers the vehicle by 0.15 in (3.8 mm) at the axle (half the −7.6 mm diameter difference).

245/55R20 is 0.30 in shorter than 275/55R19 and 30 mm narrower, a 0.97% difference in overall diameter.

With the speedometer calibrated for 275/55R19, an indicated 60 mph is actually 59.4 mph on 245/55R20, and revolutions per mile change from 652 to 659.

245/55R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 275/55R19.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.