TireSizesFinder

265/45R21 vs 255/40R22

255/40R22 is 0.36 in (9.1 mm) shorter than 265/45R21, a −1.18% diameter difference. With the speedometer set for 265/45R21, an indicated 60 mph is 59.3 mph on 255/40R22.

Is this a safe swap?

Diameter difference −1.18%: within the ±3% guideline

By overall diameter alone, 255/40R22 falls inside the ±3% range commonly used as a guideline when replacing 265/45R21. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 265/45R21 (30.39 in) vs 255/40R22 (30.03 in)265/45R2130.39 in × 10.43 in255/40R2230.03 in × 10.04 in
Side profile and tread width, drawn to the same scale.
265/45R21 vs 255/40R22 differences
Measurement265/45R21255/40R22Difference% diff
Overall diameter30.39 in (771.9 mm)30.03 in (762.8 mm)−0.36 in (−9.1 mm)−1.18%
Sidewall height4.69 in (119.3 mm)4.02 in (102.0 mm)−0.68 in (−17.2 mm)−14.47%
Section width10.43 in (265.0 mm)10.04 in (255.0 mm)−0.39 in (−10.0 mm)−3.77%
Circumference95.47 in (2,425.0 mm)94.35 in (2,396.4 mm)−1.13 in (−28.6 mm)−1.18%
Revolutions per mile664672+8+1.19%
True speed with the speedometer calibrated for 265/45R21
IndicatedActual on 265/45R21Actual on 255/40R22Difference
30 mph30.0 mph29.6 mph−0.4 mph
60 mph60.0 mph59.3 mph−0.7 mph
75 mph75.0 mph74.1 mph−0.9 mph

Ride-height change: 255/40R22 lowers the vehicle by 0.18 in (4.6 mm) at the axle (half the −9.1 mm diameter difference).

255/40R22 is 0.36 in shorter than 265/45R21 and 10 mm narrower, a 1.18% difference in overall diameter.

With the speedometer calibrated for 265/45R21, an indicated 60 mph is actually 59.3 mph on 255/40R22, and revolutions per mile change from 664 to 672.

255/40R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 265/45R21.

Size pages

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