SidewallerTire & wheel calculators

255/50R20 vs 255/55R20

255/55R20 is 3.3% taller (+1.00 in) and the same width than 255/50R20.

Caution
Check before you buy

255/55R20 is 3.3% taller than 255/50R20. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock.

255/50R20255/55R20Change
Diameter30.04″31.04″+1.00″+3.3%
Width10.04″10.04″0.00″0.0%
Sidewall5.02″5.52″+0.50″+10.0%
Circumference94.4″97.5″+3.2″+3.3%
Wheel20″20″Same
Revs per mile671650−22
SideTread
255/50R20255/55R20
Speedometer shows 60 mph62.0mph

Real speed on 255/55R20.

Ground clearance+0.50in

Change in height under the axle.

Width per side0.00in

On the same wheel, split inboard and outboard.

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255/50R20 or 255/55R20?

Can I use 255/55R20 instead of 255/50R20?

255/55R20 is 3.3% taller than 255/50R20. 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 255/55R20 you are really doing 62.0 mph if the speedometer was set up for 255/50R20. Going the other way, 255/50R20 would make it read 58.1 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.50 in (+13 mm) under the axle.

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