225/40R17 vs 245/40R17

245/40R17 is 0.63 in (16.0 mm) taller than 225/40R17, a +2.62% diameter difference. With the speedometer set for 225/40R17, an indicated 60 mph is 61.6 mph on 245/40R17.

Is this a safe swap?

Diameter difference +2.62%: within the ±3% guideline

By overall diameter alone, 245/40R17 falls inside the ±3% range commonly used as a guideline when replacing 225/40R17. 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 245/40R17 differences
Measurement	225/40R17	245/40R17	Difference	% diff
Overall diameter	24.09 in (611.8 mm)	24.72 in (627.8 mm)	+0.63 in (+16.0 mm)	+2.62%
Sidewall height	3.54 in (90.0 mm)	3.86 in (98.0 mm)	+0.31 in (+8.0 mm)	+8.89%
Section width	8.86 in (225.0 mm)	9.65 in (245.0 mm)	+0.79 in (+20.0 mm)	+8.89%
Circumference	75.67 in (1,922.0 mm)	77.65 in (1,972.3 mm)	+1.98 in (+50.3 mm)	+2.62%
Revolutions per mile	837	816	−21	−2.55%

True speed with the speedometer calibrated for 225/40R17
Indicated	Actual on 225/40R17	Actual on 245/40R17	Difference
30 mph	30.0 mph	30.8 mph	+0.8 mph
60 mph	60.0 mph	61.6 mph	+1.6 mph
75 mph	75.0 mph	77.0 mph	+2.0 mph

Ride-height change: 245/40R17 raises the vehicle by 0.31 in (8.0 mm) at the axle (half the +16.0 mm diameter difference).

245/40R17 is 0.63 in taller than 225/40R17 and 20 mm wider, a 2.62% difference in overall diameter.

With the speedometer calibrated for 225/40R17, an indicated 60 mph is actually 61.6 mph on 245/40R17, and revolutions per mile change from 837 to 816.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 225/40R17

Other comparisons with 245/40R17

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