SidewallerTire & wheel calculators

225/60R18 vs 275/40R20

275/40R20 is 0.1% taller (+0.03 in) and 1.97 in wider than 225/60R18.

OK
Close match

275/40R20 is 0.1% taller than 225/60R18. That is inside the ±3% most shops treat as a straight swap.

225/60R18275/40R20Change
Diameter28.63″28.66″+0.03″+0.1%
Width8.86″10.83″+1.97″+22.2%
Sidewall5.31″4.33″−0.98″−18.5%
Circumference89.9″90.0″+0.1″+0.1%
Wheel18″20″+2″
Revs per mile704704−1
SideTread
225/60R18275/40R20
Speedometer shows 60 mph60.1mph

Real speed on 275/40R20.

Ground clearance+0.02in

Change in height under the axle.

Width per side+0.98in

On the same wheel, split inboard and outboard.

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225/60R18 or 275/40R20?

Can I use 275/40R20 instead of 225/60R18?

275/40R20 is 0.1% taller than 225/60R18. That is inside the ±3% most shops treat as a straight swap. 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 275/40R20 you are really doing 60.1 mph if the speedometer was set up for 225/60R18. Going the other way, 225/60R18 would make it read 59.9 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.02 in (+0 mm) under the axle.

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