SidewallerTire & wheel calculators

225/55R18 vs 255/55R18

255/55R18 is 4.7% taller (+1.30 in) and 1.18 in wider than 225/55R18.

Caution
Check before you buy

255/55R18 is 4.7% taller than 225/55R18. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock.

225/55R18255/55R18Change
Diameter27.74″29.04″+1.30″+4.7%
Width8.86″10.04″+1.18″+13.3%
Sidewall4.87″5.52″+0.65″+13.3%
Circumference87.2″91.2″+4.1″+4.7%
Wheel18″18″Same
Revs per mile727694−33
SideTread
225/55R18255/55R18
Speedometer shows 60 mph62.8mph

Real speed on 255/55R18.

Ground clearance+0.65in

Change in height under the axle.

Width per side+0.59in

On the same wheel, split inboard and outboard.

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225/55R18 or 255/55R18?

Can I use 255/55R18 instead of 225/55R18?

255/55R18 is 4.7% taller than 225/55R18. 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 255/55R18 you are really doing 62.8 mph if the speedometer was set up for 225/55R18. Going the other way, 225/55R18 would make it read 57.3 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.65 in (+17 mm) under the axle.

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