255/40R22 vs 285/30R24

285/30R24 is 0.70 in (17.8 mm) taller than 255/40R22, a +2.33% diameter difference. With the speedometer set for 255/40R22, an indicated 60 mph is 61.4 mph on 285/30R24.

Is this a safe swap?

Diameter difference +2.33%: within the ±3% guideline

By overall diameter alone, 285/30R24 falls inside the ±3% range commonly used as a guideline when replacing 255/40R22. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

255/40R22 vs 285/30R24 differences
Measurement	255/40R22	285/30R24	Difference	% diff
Overall diameter	30.03 in (762.8 mm)	30.73 in (780.6 mm)	+0.70 in (+17.8 mm)	+2.33%
Sidewall height	4.02 in (102.0 mm)	3.37 in (85.5 mm)	−0.65 in (−16.5 mm)	−16.18%
Section width	10.04 in (255.0 mm)	11.22 in (285.0 mm)	+1.18 in (+30.0 mm)	+11.76%
Circumference	94.35 in (2,396.4 mm)	96.55 in (2,452.3 mm)	+2.20 in (+55.9 mm)	+2.33%
Revolutions per mile	672	656	−15	−2.28%

True speed with the speedometer calibrated for 255/40R22
Indicated	Actual on 255/40R22	Actual on 285/30R24	Difference
30 mph	30.0 mph	30.7 mph	+0.7 mph
60 mph	60.0 mph	61.4 mph	+1.4 mph
75 mph	75.0 mph	76.8 mph	+1.8 mph

Ride-height change: 285/30R24 raises the vehicle by 0.35 in (8.9 mm) at the axle (half the +17.8 mm diameter difference).

285/30R24 is 0.70 in taller than 255/40R22 and 30 mm wider, a 2.33% difference in overall diameter.

With the speedometer calibrated for 255/40R22, an indicated 60 mph is actually 61.4 mph on 285/30R24, and revolutions per mile change from 672 to 656.

285/30R24 mounts on a 24-inch wheel, a plus-2 fitment from the 22-inch wheel of 255/40R22.

Size pages

Other comparisons with 255/40R22

Other comparisons with 285/30R24

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.