225/40R17 vs 205/45R17

205/45R17 is 0.18 in (4.5 mm) taller than 225/40R17, a +0.74% diameter difference. With the speedometer set for 225/40R17, an indicated 60 mph is 60.4 mph on 205/45R17.

Is this a safe swap?

Diameter difference +0.74%: under 1%

By overall diameter alone, 205/45R17 is a near match for 225/40R17; 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.

225/40R17 vs 205/45R17 differences
Measurement	225/40R17	205/45R17	Difference	% diff
Overall diameter	24.09 in (611.8 mm)	24.26 in (616.3 mm)	+0.18 in (+4.5 mm)	+0.74%
Sidewall height	3.54 in (90.0 mm)	3.63 in (92.3 mm)	+0.09 in (+2.3 mm)	+2.50%
Section width	8.86 in (225.0 mm)	8.07 in (205.0 mm)	−0.79 in (−20.0 mm)	−8.89%
Circumference	75.67 in (1,922.0 mm)	76.23 in (1,936.2 mm)	+0.56 in (+14.1 mm)	+0.74%
Revolutions per mile	837	831	−6	−0.73%

True speed with the speedometer calibrated for 225/40R17
Indicated	Actual on 225/40R17	Actual on 205/45R17	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.4 mph	+0.4 mph
75 mph	75.0 mph	75.6 mph	+0.6 mph

Ride-height change: 205/45R17 raises the vehicle by 0.09 in (2.3 mm) at the axle (half the +4.5 mm diameter difference).

205/45R17 is 0.18 in taller than 225/40R17 and 20 mm narrower, a 0.74% difference in overall diameter.

With the speedometer calibrated for 225/40R17, an indicated 60 mph is actually 60.4 mph on 205/45R17, and revolutions per mile change from 837 to 831.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 225/40R17

Other comparisons with 205/45R17

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