TireSizesFinder

305/30R21 vs 275/30R22

275/30R22 is 0.29 in (7.4 mm) taller than 305/30R21, a +1.03% diameter difference. With the speedometer set for 305/30R21, an indicated 60 mph is 60.6 mph on 275/30R22.

Is this a safe swap?

Diameter difference +1.03%: within the ±3% guideline

By overall diameter alone, 275/30R22 falls inside the ±3% range commonly used as a guideline when replacing 305/30R21. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 305/30R21 (28.20 in) vs 275/30R22 (28.50 in)305/30R2128.20 in × 12.01 in275/30R2228.50 in × 10.83 in
Side profile and tread width, drawn to the same scale.
305/30R21 vs 275/30R22 differences
Measurement305/30R21275/30R22Difference% diff
Overall diameter28.20 in (716.4 mm)28.50 in (723.8 mm)+0.29 in (+7.4 mm)+1.03%
Sidewall height3.60 in (91.5 mm)3.25 in (82.5 mm)−0.35 in (−9.0 mm)−9.84%
Section width12.01 in (305.0 mm)10.83 in (275.0 mm)−1.18 in (−30.0 mm)−9.84%
Circumference88.61 in (2,250.6 mm)89.52 in (2,273.9 mm)+0.92 in (+23.2 mm)+1.03%
Revolutions per mile715708−7−1.02%
True speed with the speedometer calibrated for 305/30R21
IndicatedActual on 305/30R21Actual on 275/30R22Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.6 mph+0.6 mph
75 mph75.0 mph75.8 mph+0.8 mph

Ride-height change: 275/30R22 raises the vehicle by 0.15 in (3.7 mm) at the axle (half the +7.4 mm diameter difference).

275/30R22 is 0.29 in taller than 305/30R21 and 30 mm narrower, a 1.03% difference in overall diameter.

With the speedometer calibrated for 305/30R21, an indicated 60 mph is actually 60.6 mph on 275/30R22, and revolutions per mile change from 715 to 708.

275/30R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 305/30R21.

Size pages

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