225/50R15 vs 225/40R17

225/40R17 is 0.23 in (5.8 mm) taller than 225/50R15, a +0.96% diameter difference. With the speedometer set for 225/50R15, an indicated 60 mph is 60.6 mph on 225/40R17.

Is this a safe swap?

Diameter difference +0.96%: under 1%

By overall diameter alone, 225/40R17 is a near match for 225/50R15; 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.

225/50R15 vs 225/40R17 differences
Measurement	225/50R15	225/40R17	Difference	% diff
Overall diameter	23.86 in (606.0 mm)	24.09 in (611.8 mm)	+0.23 in (+5.8 mm)	+0.96%
Sidewall height	4.43 in (112.5 mm)	3.54 in (90.0 mm)	−0.89 in (−22.5 mm)	−20.00%
Section width	8.86 in (225.0 mm)	8.86 in (225.0 mm)	0.00 in (0.0 mm)	0.00%
Circumference	74.95 in (1,903.8 mm)	75.67 in (1,922.0 mm)	+0.72 in (+18.2 mm)	+0.96%
Revolutions per mile	845	837	−8	−0.95%

True speed with the speedometer calibrated for 225/50R15
Indicated	Actual on 225/50R15	Actual on 225/40R17	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	75.7 mph	+0.7 mph

Ride-height change: 225/40R17 raises the vehicle by 0.11 in (2.9 mm) at the axle (half the +5.8 mm diameter difference).

225/40R17 is 0.23 in taller than 225/50R15 and the same width, a 0.96% difference in overall diameter.

With the speedometer calibrated for 225/50R15, an indicated 60 mph is actually 60.6 mph on 225/40R17, and revolutions per mile change from 845 to 837.

225/40R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 225/50R15.

Size pages

Other comparisons with 225/50R15

Other comparisons with 225/40R17

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