205/50R15 vs 225/40R16

225/40R16 is 0.02 in (0.4 mm) taller than 205/50R15, a +0.07% diameter difference. With the speedometer set for 205/50R15, an indicated 60 mph is 60.0 mph on 225/40R16.

Is this a safe swap?

Diameter difference +0.07%: under 1%

By overall diameter alone, 225/40R16 is a near match for 205/50R15; 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.

205/50R15 vs 225/40R16 differences
Measurement	205/50R15	225/40R16	Difference	% diff
Overall diameter	23.07 in (586.0 mm)	23.09 in (586.4 mm)	+0.02 in (+0.4 mm)	+0.07%
Sidewall height	4.04 in (102.5 mm)	3.54 in (90.0 mm)	−0.49 in (−12.5 mm)	−12.20%
Section width	8.07 in (205.0 mm)	8.86 in (225.0 mm)	+0.79 in (+20.0 mm)	+9.76%
Circumference	72.48 in (1,841.0 mm)	72.53 in (1,842.2 mm)	+0.05 in (+1.3 mm)	+0.07%
Revolutions per mile	874	874	−1	−0.07%

True speed with the speedometer calibrated for 205/50R15
Indicated	Actual on 205/50R15	Actual on 225/40R16	Difference
30 mph	30.0 mph	30.0 mph	0.0 mph
60 mph	60.0 mph	60.0 mph	0.0 mph
75 mph	75.0 mph	75.1 mph	+0.1 mph

Ride-height change: 225/40R16 raises the vehicle by 0.01 in (0.2 mm) at the axle (half the +0.4 mm diameter difference).

225/40R16 is 0.02 in taller than 205/50R15 and 20 mm wider, a 0.07% difference in overall diameter.

With the speedometer calibrated for 205/50R15, an indicated 60 mph is actually 60.0 mph on 225/40R16, and revolutions per mile change from 874 to 874.

225/40R16 mounts on a 16-inch wheel, a plus-1 fitment from the 15-inch wheel of 205/50R15.

Size pages

Other comparisons with 205/50R15

Other comparisons with 225/40R16

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