245/45R20 vs 255/35R22

255/35R22 is 0.35 in (8.8 mm) taller than 245/45R20, a +1.21% diameter difference. With the speedometer set for 245/45R20, an indicated 60 mph is 60.7 mph on 255/35R22.

Is this a safe swap?

Diameter difference +1.21%: within the ±3% guideline

By overall diameter alone, 255/35R22 falls inside the ±3% range commonly used as a guideline when replacing 245/45R20. 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.

245/45R20 vs 255/35R22 differences
Measurement	245/45R20	255/35R22	Difference	% diff
Overall diameter	28.68 in (728.5 mm)	29.03 in (737.3 mm)	+0.35 in (+8.8 mm)	+1.21%
Sidewall height	4.34 in (110.3 mm)	3.51 in (89.3 mm)	−0.83 in (−21.0 mm)	−19.05%
Section width	9.65 in (245.0 mm)	10.04 in (255.0 mm)	+0.39 in (+10.0 mm)	+4.08%
Circumference	90.10 in (2,288.7 mm)	91.19 in (2,316.3 mm)	+1.09 in (+27.6 mm)	+1.21%
Revolutions per mile	703	695	−8	−1.19%

True speed with the speedometer calibrated for 245/45R20
Indicated	Actual on 245/45R20	Actual on 255/35R22	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.7 mph	+0.7 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 255/35R22 raises the vehicle by 0.17 in (4.4 mm) at the axle (half the +8.8 mm diameter difference).

255/35R22 is 0.35 in taller than 245/45R20 and 10 mm wider, a 1.21% difference in overall diameter.

With the speedometer calibrated for 245/45R20, an indicated 60 mph is actually 60.7 mph on 255/35R22, and revolutions per mile change from 703 to 695.

255/35R22 mounts on a 22-inch wheel, a plus-2 fitment from the 20-inch wheel of 245/45R20.

Size pages

Other comparisons with 245/45R20

Other comparisons with 255/35R22

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