SidewallerTire & wheel calculators

275/40R18 vs 225/55R18

225/55R18 is 4.1% taller (+1.08 in) and 1.97 in narrower than 275/40R18.

Caution
Check before you buy

225/55R18 is 4.1% taller than 275/40R18. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock.

275/40R18225/55R18Change
Diameter26.66″27.74″+1.08″+4.1%
Width10.83″8.86″−1.97″−18.2%
Sidewall4.33″4.87″+0.54″+12.5%
Circumference83.8″87.2″+3.4″+4.1%
Wheel18″18″Same
Revs per mile756727−30
SideTread
275/40R18225/55R18
Speedometer shows 60 mph62.4mph

Real speed on 225/55R18.

Ground clearance+0.54in

Change in height under the axle.

Width per side−0.98in

On the same wheel, split inboard and outboard.

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275/40R18 or 225/55R18?

Can I use 225/55R18 instead of 275/40R18?

225/55R18 is 4.1% taller than 275/40R18. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock. 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 225/55R18 you are really doing 62.4 mph if the speedometer was set up for 275/40R18. Going the other way, 275/40R18 would make it read 57.7 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.54 in (+14 mm) under the axle.

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