225/35R20 vs 245/35R20

245/35R20 is 0.55 in (14.0 mm) taller than 225/35R20, a +2.10% diameter difference. With the speedometer set for 225/35R20, an indicated 60 mph is 61.3 mph on 245/35R20.

Is this a safe swap?

Diameter difference +2.10%: within the ±3% guideline

By overall diameter alone, 245/35R20 falls inside the ±3% range commonly used as a guideline when replacing 225/35R20. 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.

225/35R20 vs 245/35R20 differences
Measurement	225/35R20	245/35R20	Difference	% diff
Overall diameter	26.20 in (665.5 mm)	26.75 in (679.5 mm)	+0.55 in (+14.0 mm)	+2.10%
Sidewall height	3.10 in (78.8 mm)	3.38 in (85.8 mm)	+0.28 in (+7.0 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	82.31 in (2,090.7 mm)	84.04 in (2,134.7 mm)	+1.73 in (+44.0 mm)	+2.10%
Revolutions per mile	770	754	−16	−2.06%

True speed with the speedometer calibrated for 225/35R20
Indicated	Actual on 225/35R20	Actual on 245/35R20	Difference
30 mph	30.0 mph	30.6 mph	+0.6 mph
60 mph	60.0 mph	61.3 mph	+1.3 mph
75 mph	75.0 mph	76.6 mph	+1.6 mph

Ride-height change: 245/35R20 raises the vehicle by 0.28 in (7.0 mm) at the axle (half the +14.0 mm diameter difference).

245/35R20 is 0.55 in taller than 225/35R20 and 20 mm wider, a 2.10% difference in overall diameter.

With the speedometer calibrated for 225/35R20, an indicated 60 mph is actually 61.3 mph on 245/35R20, and revolutions per mile change from 770 to 754.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 225/35R20

Other comparisons with 245/35R20

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