TireSizesFinder

325/30R21 vs 275/30R22

275/30R22 is 0.18 in (4.6 mm) shorter than 325/30R21, a −0.63% diameter difference. With the speedometer set for 325/30R21, an indicated 60 mph is 59.6 mph on 275/30R22.

Is this a safe swap?

Diameter difference −0.63%: under 1%

By overall diameter alone, 275/30R22 is a near match for 325/30R21; 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: 325/30R21 (28.68 in) vs 275/30R22 (28.50 in)325/30R2128.68 in × 12.80 in275/30R2228.50 in × 10.83 in
Side profile and tread width, drawn to the same scale.
325/30R21 vs 275/30R22 differences
Measurement325/30R21275/30R22Difference% diff
Overall diameter28.68 in (728.4 mm)28.50 in (723.8 mm)−0.18 in (−4.6 mm)−0.63%
Sidewall height3.84 in (97.5 mm)3.25 in (82.5 mm)−0.59 in (−15.0 mm)−15.38%
Section width12.80 in (325.0 mm)10.83 in (275.0 mm)−1.97 in (−50.0 mm)−15.38%
Circumference90.09 in (2,288.3 mm)89.52 in (2,273.9 mm)−0.57 in (−14.5 mm)−0.63%
Revolutions per mile703708+4+0.64%
True speed with the speedometer calibrated for 325/30R21
IndicatedActual on 325/30R21Actual on 275/30R22Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.6 mph−0.4 mph
75 mph75.0 mph74.5 mph−0.5 mph

Ride-height change: 275/30R22 lowers the vehicle by 0.09 in (2.3 mm) at the axle (half the −4.6 mm diameter difference).

275/30R22 is 0.18 in shorter than 325/30R21 and 50 mm narrower, a 0.63% difference in overall diameter.

With the speedometer calibrated for 325/30R21, an indicated 60 mph is actually 59.6 mph on 275/30R22, and revolutions per mile change from 703 to 708.

275/30R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 325/30R21.

Size pages

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