215/65R16 vs 295/40R18

295/40R18 is 0.29 in (7.3 mm) taller than 215/65R16, a +1.06% diameter difference. With the speedometer set for 215/65R16, an indicated 60 mph is 60.6 mph on 295/40R18.

Is this a safe swap?

Diameter difference +1.06%: within the ±3% guideline

By overall diameter alone, 295/40R18 falls inside the ±3% range commonly used as a guideline when replacing 215/65R16. 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.

215/65R16 vs 295/40R18 differences
Measurement	215/65R16	295/40R18	Difference	% diff
Overall diameter	27.00 in (685.9 mm)	27.29 in (693.2 mm)	+0.29 in (+7.3 mm)	+1.06%
Sidewall height	5.50 in (139.8 mm)	4.65 in (118.0 mm)	−0.86 in (−21.7 mm)	−15.56%
Section width	8.46 in (215.0 mm)	11.61 in (295.0 mm)	+3.15 in (+80.0 mm)	+37.21%
Circumference	84.84 in (2,154.8 mm)	85.74 in (2,177.8 mm)	+0.90 in (+22.9 mm)	+1.06%
Revolutions per mile	747	739	−8	−1.05%

True speed with the speedometer calibrated for 215/65R16
Indicated	Actual on 215/65R16	Actual on 295/40R18	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.6 mph	+0.6 mph
75 mph	75.0 mph	75.8 mph	+0.8 mph

Ride-height change: 295/40R18 raises the vehicle by 0.14 in (3.7 mm) at the axle (half the +7.3 mm diameter difference).

295/40R18 is 0.29 in taller than 215/65R16 and 80 mm wider, a 1.06% difference in overall diameter.

With the speedometer calibrated for 215/65R16, an indicated 60 mph is actually 60.6 mph on 295/40R18, and revolutions per mile change from 747 to 739.

295/40R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 215/65R16.

Size pages

Other comparisons with 215/65R16

Other comparisons with 295/40R18

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