TireSizesFinder

265/45R19 vs 265/40R20

265/40R20 is 0.04 in (1.1 mm) shorter than 265/45R19, a −0.15% diameter difference. With the speedometer set for 265/45R19, an indicated 60 mph is 59.9 mph on 265/40R20.

Is this a safe swap?

Diameter difference −0.15%: under 1%

By overall diameter alone, 265/40R20 is a near match for 265/45R19; 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: 265/45R19 (28.39 in) vs 265/40R20 (28.35 in)265/45R1928.39 in × 10.43 in265/40R2028.35 in × 10.43 in
Side profile and tread width, drawn to the same scale.
265/45R19 vs 265/40R20 differences
Measurement265/45R19265/40R20Difference% diff
Overall diameter28.39 in (721.1 mm)28.35 in (720.0 mm)−0.04 in (−1.1 mm)−0.15%
Sidewall height4.69 in (119.3 mm)4.17 in (106.0 mm)−0.52 in (−13.2 mm)−11.11%
Section width10.43 in (265.0 mm)10.43 in (265.0 mm)0.00 in (0.0 mm)0.00%
Circumference89.19 in (2,265.4 mm)89.05 in (2,261.9 mm)−0.14 in (−3.5 mm)−0.15%
Revolutions per mile710711+1+0.15%
True speed with the speedometer calibrated for 265/45R19
IndicatedActual on 265/45R19Actual on 265/40R20Difference
30 mph30.0 mph30.0 mph0.0 mph
60 mph60.0 mph59.9 mph−0.1 mph
75 mph75.0 mph74.9 mph−0.1 mph

Ride-height change: 265/40R20 lowers the vehicle by 0.02 in (0.5 mm) at the axle (half the −1.1 mm diameter difference).

265/40R20 is 0.04 in shorter than 265/45R19 and the same width, a 0.15% difference in overall diameter.

With the speedometer calibrated for 265/45R19, an indicated 60 mph is actually 59.9 mph on 265/40R20, and revolutions per mile change from 710 to 711.

265/40R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 265/45R19.

Size pages

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