TireSizesFinder

245/50R19 vs 245/45R20

245/45R20 is 0.04 in (0.9 mm) taller than 245/50R19, a +0.12% diameter difference. With the speedometer set for 245/50R19, an indicated 60 mph is 60.1 mph on 245/45R20.

Is this a safe swap?

Diameter difference +0.12%: under 1%

By overall diameter alone, 245/45R20 is a near match for 245/50R19; 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: 245/50R19 (28.65 in) vs 245/45R20 (28.68 in)245/50R1928.65 in × 9.65 in245/45R2028.68 in × 9.65 in
Side profile and tread width, drawn to the same scale.
245/50R19 vs 245/45R20 differences
Measurement245/50R19245/45R20Difference% diff
Overall diameter28.65 in (727.6 mm)28.68 in (728.5 mm)+0.04 in (+0.9 mm)+0.12%
Sidewall height4.82 in (122.5 mm)4.34 in (110.3 mm)−0.48 in (−12.2 mm)−10.00%
Section width9.65 in (245.0 mm)9.65 in (245.0 mm)0.00 in (0.0 mm)0.00%
Circumference89.99 in (2,285.8 mm)90.10 in (2,288.7 mm)+0.11 in (+2.8 mm)+0.12%
Revolutions per mile704703−1−0.12%
True speed with the speedometer calibrated for 245/50R19
IndicatedActual on 245/50R19Actual on 245/45R20Difference
30 mph30.0 mph30.0 mph0.0 mph
60 mph60.0 mph60.1 mph+0.1 mph
75 mph75.0 mph75.1 mph+0.1 mph

Ride-height change: 245/45R20 raises the vehicle by 0.02 in (0.5 mm) at the axle (half the +0.9 mm diameter difference).

245/45R20 is 0.04 in taller than 245/50R19 and the same width, a 0.12% difference in overall diameter.

With the speedometer calibrated for 245/50R19, an indicated 60 mph is actually 60.1 mph on 245/45R20, and revolutions per mile change from 704 to 703.

245/45R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 245/50R19.

Size pages

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