235/60R16 vs 295/40R18

295/40R18 is 0.19 in (4.8 mm) taller than 235/60R16, a +0.70% diameter difference. With the speedometer set for 235/60R16, an indicated 60 mph is 60.4 mph on 295/40R18.

Is this a safe swap?

Diameter difference +0.70%: under 1%

By overall diameter alone, 295/40R18 is a near match for 235/60R16; the speedometer changes by less than 1%. 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.

235/60R16 vs 295/40R18 differences
Measurement	235/60R16	295/40R18	Difference	% diff
Overall diameter	27.10 in (688.4 mm)	27.29 in (693.2 mm)	+0.19 in (+4.8 mm)	+0.70%
Sidewall height	5.55 in (141.0 mm)	4.65 in (118.0 mm)	−0.91 in (−23.0 mm)	−16.31%
Section width	9.25 in (235.0 mm)	11.61 in (295.0 mm)	+2.36 in (+60.0 mm)	+25.53%
Circumference	85.14 in (2,162.7 mm)	85.74 in (2,177.8 mm)	+0.59 in (+15.1 mm)	+0.70%
Revolutions per mile	744	739	−5	−0.69%

True speed with the speedometer calibrated for 235/60R16
Indicated	Actual on 235/60R16	Actual on 295/40R18	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.4 mph	+0.4 mph
75 mph	75.0 mph	75.5 mph	+0.5 mph

Ride-height change: 295/40R18 raises the vehicle by 0.09 in (2.4 mm) at the axle (half the +4.8 mm diameter difference).

295/40R18 is 0.19 in taller than 235/60R16 and 60 mm wider, a 0.70% difference in overall diameter.

With the speedometer calibrated for 235/60R16, an indicated 60 mph is actually 60.4 mph on 295/40R18, and revolutions per mile change from 744 to 739.

295/40R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 235/60R16.

Size pages

Other comparisons with 235/60R16

Other comparisons with 295/40R18

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