TireSizesFinder

245/60R18 vs 265/45R20

265/45R20 is 0.19 in (4.7 mm) shorter than 245/60R18, a −0.63% diameter difference. With the speedometer set for 245/60R18, an indicated 60 mph is 59.6 mph on 265/45R20.

Is this a safe swap?

Diameter difference −0.63%: under 1%

By overall diameter alone, 265/45R20 is a near match for 245/60R18; 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: 245/60R18 (29.57 in) vs 265/45R20 (29.39 in)245/60R1829.57 in × 9.65 in265/45R2029.39 in × 10.43 in
Side profile and tread width, drawn to the same scale.
245/60R18 vs 265/45R20 differences
Measurement245/60R18265/45R20Difference% diff
Overall diameter29.57 in (751.2 mm)29.39 in (746.5 mm)−0.19 in (−4.7 mm)−0.63%
Sidewall height5.79 in (147.0 mm)4.69 in (119.3 mm)−1.09 in (−27.7 mm)−18.88%
Section width9.65 in (245.0 mm)10.43 in (265.0 mm)+0.79 in (+20.0 mm)+8.16%
Circumference92.91 in (2,360.0 mm)92.33 in (2,345.2 mm)−0.58 in (−14.8 mm)−0.63%
Revolutions per mile682686+4+0.63%
True speed with the speedometer calibrated for 245/60R18
IndicatedActual on 245/60R18Actual on 265/45R20Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.6 mph−0.4 mph
75 mph75.0 mph74.5 mph−0.5 mph

Ride-height change: 265/45R20 lowers the vehicle by 0.09 in (2.4 mm) at the axle (half the −4.7 mm diameter difference).

265/45R20 is 0.19 in shorter than 245/60R18 and 20 mm wider, a 0.63% difference in overall diameter.

With the speedometer calibrated for 245/60R18, an indicated 60 mph is actually 59.6 mph on 265/45R20, and revolutions per mile change from 682 to 686.

265/45R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 245/60R18.

Size pages

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