TireSizesFinder

275/40R21 vs 255/40R22

255/40R22 is 0.37 in (9.4 mm) taller than 275/40R21, a +1.25% diameter difference. With the speedometer set for 275/40R21, an indicated 60 mph is 60.7 mph on 255/40R22.

Is this a safe swap?

Diameter difference +1.25%: within the ±3% guideline

By overall diameter alone, 255/40R22 falls inside the ±3% range commonly used as a guideline when replacing 275/40R21. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 275/40R21 (29.66 in) vs 255/40R22 (30.03 in)275/40R2129.66 in × 10.83 in255/40R2230.03 in × 10.04 in
Side profile and tread width, drawn to the same scale.
275/40R21 vs 255/40R22 differences
Measurement275/40R21255/40R22Difference% diff
Overall diameter29.66 in (753.4 mm)30.03 in (762.8 mm)+0.37 in (+9.4 mm)+1.25%
Sidewall height4.33 in (110.0 mm)4.02 in (102.0 mm)−0.31 in (−8.0 mm)−7.27%
Section width10.83 in (275.0 mm)10.04 in (255.0 mm)−0.79 in (−20.0 mm)−7.27%
Circumference93.18 in (2,366.9 mm)94.35 in (2,396.4 mm)+1.16 in (+29.5 mm)+1.25%
Revolutions per mile680672−8−1.23%
True speed with the speedometer calibrated for 275/40R21
IndicatedActual on 275/40R21Actual on 255/40R22Difference
30 mph30.0 mph30.4 mph+0.4 mph
60 mph60.0 mph60.7 mph+0.7 mph
75 mph75.0 mph75.9 mph+0.9 mph

Ride-height change: 255/40R22 raises the vehicle by 0.19 in (4.7 mm) at the axle (half the +9.4 mm diameter difference).

255/40R22 is 0.37 in taller than 275/40R21 and 20 mm narrower, a 1.25% difference in overall diameter.

With the speedometer calibrated for 275/40R21, an indicated 60 mph is actually 60.7 mph on 255/40R22, and revolutions per mile change from 680 to 672.

255/40R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 275/40R21.

Size pages

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Other comparisons with 255/40R22

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