TireSizesFinder

235/60R18 vs 265/45R20

265/45R20 is 0.29 in (7.3 mm) taller than 235/60R18, a +0.99% diameter difference. With the speedometer set for 235/60R18, an indicated 60 mph is 60.6 mph on 265/45R20.

Is this a safe swap?

Diameter difference +0.99%: under 1%

By overall diameter alone, 265/45R20 is a near match for 235/60R18; 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: 235/60R18 (29.10 in) vs 265/45R20 (29.39 in)235/60R1829.10 in × 9.25 in265/45R2029.39 in × 10.43 in
Side profile and tread width, drawn to the same scale.
235/60R18 vs 265/45R20 differences
Measurement235/60R18265/45R20Difference% diff
Overall diameter29.10 in (739.2 mm)29.39 in (746.5 mm)+0.29 in (+7.3 mm)+0.99%
Sidewall height5.55 in (141.0 mm)4.69 in (119.3 mm)−0.86 in (−21.7 mm)−15.43%
Section width9.25 in (235.0 mm)10.43 in (265.0 mm)+1.18 in (+30.0 mm)+12.77%
Circumference91.43 in (2,322.3 mm)92.33 in (2,345.2 mm)+0.90 in (+22.9 mm)+0.99%
Revolutions per mile693686−7−0.98%
True speed with the speedometer calibrated for 235/60R18
IndicatedActual on 235/60R18Actual on 265/45R20Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.6 mph+0.6 mph
75 mph75.0 mph75.7 mph+0.7 mph

Ride-height change: 265/45R20 raises the vehicle by 0.14 in (3.6 mm) at the axle (half the +7.3 mm diameter difference).

265/45R20 is 0.29 in taller than 235/60R18 and 30 mm wider, a 0.99% difference in overall diameter.

With the speedometer calibrated for 235/60R18, an indicated 60 mph is actually 60.6 mph on 265/45R20, and revolutions per mile change from 693 to 686.

265/45R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 235/60R18.

Size pages

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