TireSizesFinder

245/60R18 vs 295/40R20

295/40R20 is 0.28 in (7.2 mm) shorter than 245/60R18, a −0.96% diameter difference. With the speedometer set for 245/60R18, an indicated 60 mph is 59.4 mph on 295/40R20.

Is this a safe swap?

Diameter difference −0.96%: under 1%

By overall diameter alone, 295/40R20 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 295/40R20 (29.29 in)245/60R1829.57 in × 9.65 in295/40R2029.29 in × 11.61 in
Side profile and tread width, drawn to the same scale.
245/60R18 vs 295/40R20 differences
Measurement245/60R18295/40R20Difference% diff
Overall diameter29.57 in (751.2 mm)29.29 in (744.0 mm)−0.28 in (−7.2 mm)−0.96%
Sidewall height5.79 in (147.0 mm)4.65 in (118.0 mm)−1.14 in (−29.0 mm)−19.73%
Section width9.65 in (245.0 mm)11.61 in (295.0 mm)+1.97 in (+50.0 mm)+20.41%
Circumference92.91 in (2,360.0 mm)92.02 in (2,337.3 mm)−0.89 in (−22.6 mm)−0.96%
Revolutions per mile682689+7+0.97%
True speed with the speedometer calibrated for 245/60R18
IndicatedActual on 245/60R18Actual on 295/40R20Difference
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: 295/40R20 lowers the vehicle by 0.14 in (3.6 mm) at the axle (half the −7.2 mm diameter difference).

295/40R20 is 0.28 in shorter than 245/60R18 and 50 mm wider, a 0.96% difference in overall diameter.

With the speedometer calibrated for 245/60R18, an indicated 60 mph is actually 59.4 mph on 295/40R20, and revolutions per mile change from 682 to 689.

295/40R20 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.