TireSizesFinder

305/40R22 vs 285/30R24

285/30R24 is 0.87 in (22.2 mm) shorter than 305/40R22, a −2.77% diameter difference. With the speedometer set for 305/40R22, an indicated 60 mph is 58.3 mph on 285/30R24.

Is this a safe swap?

Diameter difference −2.77%: within the ±3% guideline

By overall diameter alone, 285/30R24 falls inside the ±3% range commonly used as a guideline when replacing 305/40R22. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 305/40R22 (31.61 in) vs 285/30R24 (30.73 in)305/40R2231.61 in × 12.01 in285/30R2430.73 in × 11.22 in
Side profile and tread width, drawn to the same scale.
305/40R22 vs 285/30R24 differences
Measurement305/40R22285/30R24Difference% diff
Overall diameter31.61 in (802.8 mm)30.73 in (780.6 mm)−0.87 in (−22.2 mm)−2.77%
Sidewall height4.80 in (122.0 mm)3.37 in (85.5 mm)−1.44 in (−36.5 mm)−29.92%
Section width12.01 in (305.0 mm)11.22 in (285.0 mm)−0.79 in (−20.0 mm)−6.56%
Circumference99.29 in (2,522.1 mm)96.55 in (2,452.3 mm)−2.75 in (−69.7 mm)−2.77%
Revolutions per mile638656+18+2.84%
True speed with the speedometer calibrated for 305/40R22
IndicatedActual on 305/40R22Actual on 285/30R24Difference
30 mph30.0 mph29.2 mph−0.8 mph
60 mph60.0 mph58.3 mph−1.7 mph
75 mph75.0 mph72.9 mph−2.1 mph

Ride-height change: 285/30R24 lowers the vehicle by 0.44 in (11.1 mm) at the axle (half the −22.2 mm diameter difference).

285/30R24 is 0.87 in shorter than 305/40R22 and 20 mm narrower, a 2.77% difference in overall diameter.

With the speedometer calibrated for 305/40R22, an indicated 60 mph is actually 58.3 mph on 285/30R24, and revolutions per mile change from 638 to 656.

285/30R24 mounts on a 24-inch wheel, a plus-2 fitment from the 22-inch wheel of 305/40R22.

Size pages

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