265/50R20 vs 295/40R21

295/40R21 is 0.14 in (3.6 mm) shorter than 265/50R20, a −0.47% diameter difference. With the speedometer set for 265/50R20, an indicated 60 mph is 59.7 mph on 295/40R21.

Is this a safe swap?

Diameter difference −0.47%: under 1%

By overall diameter alone, 295/40R21 is a near match for 265/50R20; 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: 265/50R20 (30.43 in) vs 295/40R21 (30.29 in)265/50R2030.43 in × 10.43 in295/40R2130.29 in × 11.61 in
Side profile and tread width, drawn to the same scale.
265/50R20 vs 295/40R21 differences
Measurement265/50R20295/40R21Difference% diff
Overall diameter30.43 in (773.0 mm)30.29 in (769.4 mm)−0.14 in (−3.6 mm)−0.47%
Sidewall height5.22 in (132.5 mm)4.65 in (118.0 mm)−0.57 in (−14.5 mm)−10.94%
Section width10.43 in (265.0 mm)11.61 in (295.0 mm)+1.18 in (+30.0 mm)+11.32%
Circumference95.61 in (2,428.5 mm)95.16 in (2,417.1 mm)−0.45 in (−11.3 mm)−0.47%
Revolutions per mile663666+3+0.47%
True speed with the speedometer calibrated for 265/50R20
IndicatedActual on 265/50R20Actual on 295/40R21Difference
30 mph30.0 mph29.9 mph−0.1 mph
60 mph60.0 mph59.7 mph−0.3 mph
75 mph75.0 mph74.7 mph−0.3 mph

Ride-height change: 295/40R21 lowers the vehicle by 0.07 in (1.8 mm) at the axle (half the −3.6 mm diameter difference).

295/40R21 is 0.14 in shorter than 265/50R20 and 30 mm wider, a 0.47% difference in overall diameter.

With the speedometer calibrated for 265/50R20, an indicated 60 mph is actually 59.7 mph on 295/40R21, and revolutions per mile change from 663 to 666.

295/40R21 mounts on a 21-inch wheel, a plus-1 fitment from the 20-inch wheel of 265/50R20.

Size pages

Other comparisons with 265/50R20

Other comparisons with 295/40R21

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