TireSizesFinder

245/40R21 vs 275/30R22

275/30R22 is 0.22 in (5.6 mm) shorter than 245/40R21, a −0.77% diameter difference. With the speedometer set for 245/40R21, an indicated 60 mph is 59.5 mph on 275/30R22.

Is this a safe swap?

Diameter difference −0.77%: under 1%

By overall diameter alone, 275/30R22 is a near match for 245/40R21; 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: 245/40R21 (28.72 in) vs 275/30R22 (28.50 in)245/40R2128.72 in × 9.65 in275/30R2228.50 in × 10.83 in
Side profile and tread width, drawn to the same scale.
245/40R21 vs 275/30R22 differences
Measurement245/40R21275/30R22Difference% diff
Overall diameter28.72 in (729.4 mm)28.50 in (723.8 mm)−0.22 in (−5.6 mm)−0.77%
Sidewall height3.86 in (98.0 mm)3.25 in (82.5 mm)−0.61 in (−15.5 mm)−15.82%
Section width9.65 in (245.0 mm)10.83 in (275.0 mm)+1.18 in (+30.0 mm)+12.24%
Circumference90.22 in (2,291.5 mm)89.52 in (2,273.9 mm)−0.69 in (−17.6 mm)−0.77%
Revolutions per mile702708+5+0.77%
True speed with the speedometer calibrated for 245/40R21
IndicatedActual on 245/40R21Actual on 275/30R22Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.4 mph−0.6 mph

Ride-height change: 275/30R22 lowers the vehicle by 0.11 in (2.8 mm) at the axle (half the −5.6 mm diameter difference).

275/30R22 is 0.22 in shorter than 245/40R21 and 30 mm wider, a 0.77% difference in overall diameter.

With the speedometer calibrated for 245/40R21, an indicated 60 mph is actually 59.5 mph on 275/30R22, and revolutions per mile change from 702 to 708.

275/30R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 245/40R21.

Size pages

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