SidewallerTire & wheel calculators

255/65R18 vs 285/65R18

285/65R18 is 4.9% taller (+1.54 in) and 1.18 in wider than 255/65R18.

Caution
Check before you buy

285/65R18 is 4.9% taller than 255/65R18. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock.

255/65R18285/65R18Change
Diameter31.05″32.59″+1.54″+4.9%
Width10.04″11.22″+1.18″+11.8%
Sidewall6.53″7.29″+0.77″+11.8%
Circumference97.6″102.4″+4.8″+4.9%
Wheel18″18″Same
Revs per mile650619−31
SideTread
255/65R18285/65R18
Speedometer shows 60 mph63.0mph

Real speed on 285/65R18.

Ground clearance+0.77in

Change in height under the axle.

Width per side+0.59in

On the same wheel, split inboard and outboard.

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255/65R18 or 285/65R18?

Can I use 285/65R18 instead of 255/65R18?

285/65R18 is 4.9% taller than 255/65R18. 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 285/65R18 you are really doing 63.0 mph if the speedometer was set up for 255/65R18. Going the other way, 255/65R18 would make it read 57.2 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.77 in (+20 mm) under the axle.

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