TireSizesFinder

225/45R18 vs 225/35R20

225/35R20 is 0.23 in (5.8 mm) taller than 225/45R18, a +0.88% diameter difference. With the speedometer set for 225/45R18, an indicated 60 mph is 60.5 mph on 225/35R20.

Is this a safe swap?

Diameter difference +0.88%: under 1%

By overall diameter alone, 225/35R20 is a near match for 225/45R18; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 225/45R18 (25.97 in) vs 225/35R20 (26.20 in)225/45R1825.97 in × 8.86 in225/35R2026.20 in × 8.86 in
Side profile and tread width, drawn to the same scale.
225/45R18 vs 225/35R20 differences
Measurement225/45R18225/35R20Difference% diff
Overall diameter25.97 in (659.7 mm)26.20 in (665.5 mm)+0.23 in (+5.8 mm)+0.88%
Sidewall height3.99 in (101.3 mm)3.10 in (78.8 mm)−0.89 in (−22.5 mm)−22.22%
Section width8.86 in (225.0 mm)8.86 in (225.0 mm)0.00 in (0.0 mm)0.00%
Circumference81.59 in (2,072.5 mm)82.31 in (2,090.7 mm)+0.72 in (+18.2 mm)+0.88%
Revolutions per mile777770−7−0.87%
True speed with the speedometer calibrated for 225/45R18
IndicatedActual on 225/45R18Actual on 225/35R20Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.5 mph+0.5 mph
75 mph75.0 mph75.7 mph+0.7 mph

Ride-height change: 225/35R20 raises the vehicle by 0.11 in (2.9 mm) at the axle (half the +5.8 mm diameter difference).

225/35R20 is 0.23 in taller than 225/45R18 and the same width, a 0.88% difference in overall diameter.

With the speedometer calibrated for 225/45R18, an indicated 60 mph is actually 60.5 mph on 225/35R20, and revolutions per mile change from 777 to 770.

225/35R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 225/45R18.

Size pages

Other comparisons with 225/45R18

Other comparisons with 225/35R20

Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.