TireSizesFinder

255/40R21 vs 245/35R22

245/35R22 is 0.28 in (7.1 mm) shorter than 255/40R21, a −0.96% diameter difference. With the speedometer set for 255/40R21, an indicated 60 mph is 59.4 mph on 245/35R22.

Is this a safe swap?

Diameter difference −0.96%: under 1%

By overall diameter alone, 245/35R22 is a near match for 255/40R21; 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: 255/40R21 (29.03 in) vs 245/35R22 (28.75 in)255/40R2129.03 in × 10.04 in245/35R2228.75 in × 9.65 in
Side profile and tread width, drawn to the same scale.
255/40R21 vs 245/35R22 differences
Measurement255/40R21245/35R22Difference% diff
Overall diameter29.03 in (737.4 mm)28.75 in (730.3 mm)−0.28 in (−7.1 mm)−0.96%
Sidewall height4.02 in (102.0 mm)3.38 in (85.8 mm)−0.64 in (−16.2 mm)−15.93%
Section width10.04 in (255.0 mm)9.65 in (245.0 mm)−0.39 in (−10.0 mm)−3.92%
Circumference91.21 in (2,316.6 mm)90.33 in (2,294.3 mm)−0.88 in (−22.3 mm)−0.96%
Revolutions per mile695701+7+0.97%
True speed with the speedometer calibrated for 255/40R21
IndicatedActual on 255/40R21Actual on 245/35R22Difference
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: 245/35R22 lowers the vehicle by 0.14 in (3.6 mm) at the axle (half the −7.1 mm diameter difference).

245/35R22 is 0.28 in shorter than 255/40R21 and 10 mm narrower, a 0.96% difference in overall diameter.

With the speedometer calibrated for 255/40R21, an indicated 60 mph is actually 59.4 mph on 245/35R22, and revolutions per mile change from 695 to 701.

245/35R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 255/40R21.

Size pages

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