225/65R16 vs 295/40R18

295/40R18 is 0.22 in (5.7 mm) shorter than 225/65R16, a −0.82% diameter difference. With the speedometer set for 225/65R16, an indicated 60 mph is 59.5 mph on 295/40R18.

Is this a safe swap?

Diameter difference −0.82%: under 1%

By overall diameter alone, 295/40R18 is a near match for 225/65R16; 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.

225/65R16 vs 295/40R18 differences
Measurement	225/65R16	295/40R18	Difference	% diff
Overall diameter	27.52 in (698.9 mm)	27.29 in (693.2 mm)	−0.22 in (−5.7 mm)	−0.82%
Sidewall height	5.76 in (146.3 mm)	4.65 in (118.0 mm)	−1.11 in (−28.2 mm)	−19.32%
Section width	8.86 in (225.0 mm)	11.61 in (295.0 mm)	+2.76 in (+70.0 mm)	+31.11%
Circumference	86.44 in (2,195.7 mm)	85.74 in (2,177.8 mm)	−0.71 in (−17.9 mm)	−0.82%
Revolutions per mile	733	739	+6	+0.82%

True speed with the speedometer calibrated for 225/65R16
Indicated	Actual on 225/65R16	Actual on 295/40R18	Difference
30 mph	30.0 mph	29.8 mph	−0.2 mph
60 mph	60.0 mph	59.5 mph	−0.5 mph
75 mph	75.0 mph	74.4 mph	−0.6 mph

Ride-height change: 295/40R18 lowers the vehicle by 0.11 in (2.8 mm) at the axle (half the −5.7 mm diameter difference).

295/40R18 is 0.22 in shorter than 225/65R16 and 70 mm wider, a 0.82% difference in overall diameter.

With the speedometer calibrated for 225/65R16, an indicated 60 mph is actually 59.5 mph on 295/40R18, and revolutions per mile change from 733 to 739.

295/40R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 225/65R16.

Size pages

Other comparisons with 225/65R16

Other comparisons with 295/40R18

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