SidewallerTire & wheel calculators

275/60R20 vs 305/55R20

305/55R20 is 0.7% taller (+0.22 in) and 1.18 in wider than 275/60R20.

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Close match

305/55R20 is 0.7% taller than 275/60R20. That is inside the ±3% most shops treat as a straight swap.

275/60R20305/55R20Change
Diameter32.99″33.21″+0.22″+0.7%
Width10.83″12.01″+1.18″+10.9%
Sidewall6.50″6.60″+0.11″+1.7%
Circumference103.6″104.3″+0.7″+0.7%
Wheel20″20″Same
Revs per mile611607−4
SideTread
275/60R20305/55R20
Speedometer shows 60 mph60.4mph

Real speed on 305/55R20.

Ground clearance+0.11in

Change in height under the axle.

Width per side+0.59in

On the same wheel, split inboard and outboard.

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275/60R20 or 305/55R20?

Can I use 305/55R20 instead of 275/60R20?

305/55R20 is 0.7% taller than 275/60R20. That is inside the ±3% most shops treat as a straight swap. 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 60.4 mph if the speedometer was set up for 275/60R20. Going the other way, 275/60R20 would make it read 59.6 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.11 in (+3 mm) under the axle.

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