275/25R24 vs 285/30R24

285/30R24 is 1.32 in (33.5 mm) taller than 275/25R24, a +4.48% diameter difference. With the speedometer set for 275/25R24, an indicated 60 mph is 62.7 mph on 285/30R24.

Is this a safe swap?

Diameter difference +4.48%: outside the ±3% guideline

By overall diameter alone, 285/30R24 falls outside the ±3% range commonly used as a guideline when replacing 275/25R24; speedometer and ride-height changes are larger. 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.

275/25R24 vs 285/30R24 differences
Measurement	275/25R24	285/30R24	Difference	% diff
Overall diameter	29.41 in (747.1 mm)	30.73 in (780.6 mm)	+1.32 in (+33.5 mm)	+4.48%
Sidewall height	2.71 in (68.8 mm)	3.37 in (85.5 mm)	+0.66 in (+16.8 mm)	+24.36%
Section width	10.83 in (275.0 mm)	11.22 in (285.0 mm)	+0.39 in (+10.0 mm)	+3.64%
Circumference	92.40 in (2,347.1 mm)	96.55 in (2,452.3 mm)	+4.14 in (+105.2 mm)	+4.48%
Revolutions per mile	686	656	−29	−4.29%

True speed with the speedometer calibrated for 275/25R24
Indicated	Actual on 275/25R24	Actual on 285/30R24	Difference
30 mph	30.0 mph	31.3 mph	+1.3 mph
60 mph	60.0 mph	62.7 mph	+2.7 mph
75 mph	75.0 mph	78.4 mph	+3.4 mph

Ride-height change: 285/30R24 raises the vehicle by 0.66 in (16.8 mm) at the axle (half the +33.5 mm diameter difference).

285/30R24 is 1.32 in taller than 275/25R24 and 10 mm wider, a 4.48% difference in overall diameter.

With the speedometer calibrated for 275/25R24, an indicated 60 mph is actually 62.7 mph on 285/30R24, and revolutions per mile change from 686 to 656.

Both sizes mount on 24-inch wheels.

Size pages

Other comparisons with 275/25R24

Other comparisons with 285/30R24

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