SidewallerTire & wheel calculators

275/55R20 vs 305/55R20

305/55R20 is 4.1% taller (+1.30 in) and 1.18 in wider than 275/55R20.

Caution
Check before you buy

305/55R20 is 4.1% taller than 275/55R20. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock.

275/55R20305/55R20Change
Diameter31.91″33.21″+1.30″+4.1%
Width10.83″12.01″+1.18″+10.9%
Sidewall5.95″6.60″+0.65″+10.9%
Circumference100.2″104.3″+4.1″+4.1%
Wheel20″20″Same
Revs per mile632607−25
SideTread
275/55R20305/55R20
Speedometer shows 60 mph62.4mph

Real speed on 305/55R20.

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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275/55R20 or 305/55R20?

Can I use 305/55R20 instead of 275/55R20?

305/55R20 is 4.1% taller than 275/55R20. 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 305/55R20 you are really doing 62.4 mph if the speedometer was set up for 275/55R20. Going the other way, 275/55R20 would make it read 57.7 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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