285/40R18 vs 295/40R18

295/40R18 is 0.31 in (8.0 mm) taller than 285/40R18, a +1.17% diameter difference. With the speedometer set for 285/40R18, an indicated 60 mph is 60.7 mph on 295/40R18.

Is this a safe swap?

Diameter difference +1.17%: within the ±3% guideline

By overall diameter alone, 295/40R18 falls inside the ±3% range commonly used as a guideline when replacing 285/40R18. 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.

285/40R18 vs 295/40R18 differences
Measurement	285/40R18	295/40R18	Difference	% diff
Overall diameter	26.98 in (685.2 mm)	27.29 in (693.2 mm)	+0.31 in (+8.0 mm)	+1.17%
Sidewall height	4.49 in (114.0 mm)	4.65 in (118.0 mm)	+0.16 in (+4.0 mm)	+3.51%
Section width	11.22 in (285.0 mm)	11.61 in (295.0 mm)	+0.39 in (+10.0 mm)	+3.51%
Circumference	84.75 in (2,152.6 mm)	85.74 in (2,177.8 mm)	+0.99 in (+25.1 mm)	+1.17%
Revolutions per mile	748	739	−9	−1.15%

True speed with the speedometer calibrated for 285/40R18
Indicated	Actual on 285/40R18	Actual on 295/40R18	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.7 mph	+0.7 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 295/40R18 raises the vehicle by 0.16 in (4.0 mm) at the axle (half the +8.0 mm diameter difference).

295/40R18 is 0.31 in taller than 285/40R18 and 10 mm wider, a 1.17% difference in overall diameter.

With the speedometer calibrated for 285/40R18, an indicated 60 mph is actually 60.7 mph on 295/40R18, and revolutions per mile change from 748 to 739.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 285/40R18

Other comparisons with 295/40R18

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