195/50R16 vs 225/35R18

225/35R18 is 0.52 in (13.3 mm) taller than 195/50R16, a +2.21% diameter difference. With the speedometer set for 195/50R16, an indicated 60 mph is 61.3 mph on 225/35R18.

Is this a safe swap?

Diameter difference +2.21%: within the ±3% guideline

By overall diameter alone, 225/35R18 falls inside the ±3% range commonly used as a guideline when replacing 195/50R16. 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.

195/50R16 vs 225/35R18 differences
Measurement	195/50R16	225/35R18	Difference	% diff
Overall diameter	23.68 in (601.4 mm)	24.20 in (614.7 mm)	+0.52 in (+13.3 mm)	+2.21%
Sidewall height	3.84 in (97.5 mm)	3.10 in (78.8 mm)	−0.74 in (−18.7 mm)	−19.23%
Section width	7.68 in (195.0 mm)	8.86 in (225.0 mm)	+1.18 in (+30.0 mm)	+15.38%
Circumference	74.38 in (1,889.4 mm)	76.03 in (1,931.1 mm)	+1.65 in (+41.8 mm)	+2.21%
Revolutions per mile	852	833	−18	−2.16%

True speed with the speedometer calibrated for 195/50R16
Indicated	Actual on 195/50R16	Actual on 225/35R18	Difference
30 mph	30.0 mph	30.7 mph	+0.7 mph
60 mph	60.0 mph	61.3 mph	+1.3 mph
75 mph	75.0 mph	76.7 mph	+1.7 mph

Ride-height change: 225/35R18 raises the vehicle by 0.26 in (6.7 mm) at the axle (half the +13.3 mm diameter difference).

225/35R18 is 0.52 in taller than 195/50R16 and 30 mm wider, a 2.21% difference in overall diameter.

With the speedometer calibrated for 195/50R16, an indicated 60 mph is actually 61.3 mph on 225/35R18, and revolutions per mile change from 852 to 833.

225/35R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 195/50R16.

Size pages

Other comparisons with 195/50R16

Other comparisons with 225/35R18

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