SidewallerTire & wheel calculators

225/35R20 vs 245/40R20

245/40R20 is 5.8% taller (+1.52 in) and 0.79 in wider than 225/35R20.

Large
Big change

245/40R20 is 5.8% taller than 225/35R20. Beyond 5% you usually need a lift or leveling kit, a speedometer recalibration and sometimes new gears.

225/35R20245/40R20Change
Diameter26.20″27.72″+1.52″+5.8%
Width8.86″9.65″+0.79″+8.9%
Sidewall3.10″3.86″+0.76″+24.4%
Circumference82.3″87.1″+4.8″+5.8%
Wheel20″20″Same
Revs per mile770728−42
SideTread
225/35R20245/40R20
Speedometer shows 60 mph63.5mph

Real speed on 245/40R20.

Ground clearance+0.76in

Change in height under the axle.

Width per side+0.39in

On the same wheel, split inboard and outboard.

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225/35R20 or 245/40R20?

Can I use 245/40R20 instead of 225/35R20?

245/40R20 is 5.8% taller than 225/35R20. Beyond 5% you usually need a lift or leveling kit, a speedometer recalibration and sometimes new gears. Also match or beat the original load index and speed rating, and check that the wheel width suits the new tire.

Will my speedometer be off?

At an indicated 60 mph on 245/40R20 you are really doing 63.5 mph if the speedometer was set up for 225/35R20. Going the other way, 225/35R20 would make it read 56.7 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.76 in (+19 mm) under the axle.

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