SidewallerTire & wheel calculators

275/70R17 vs 285/55R20

285/55R20 is 0.6% taller (+0.19 in) and 0.39 in wider than 275/70R17.

OK
Close match

285/55R20 is 0.6% taller than 275/70R17. That is inside the ±3% most shops treat as a straight swap.

275/70R17285/55R20Change
Diameter32.16″32.34″+0.19″+0.6%
Width10.83″11.22″+0.39″+3.6%
Sidewall7.58″6.17″−1.41″−18.6%
Circumference101.0″101.6″+0.6″+0.6%
Wheel17″20″+3″
Revs per mile627624−4
SideTread
275/70R17285/55R20
Speedometer shows 60 mph60.3mph

Real speed on 285/55R20.

Ground clearance+0.09in

Change in height under the axle.

Width per side+0.20in

On the same wheel, split inboard and outboard.

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275/70R17 or 285/55R20?

Can I use 285/55R20 instead of 275/70R17?

285/55R20 is 0.6% taller than 275/70R17. 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 285/55R20 you are really doing 60.3 mph if the speedometer was set up for 275/70R17. Going the other way, 275/70R17 would make it read 59.7 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.09 in (+2 mm) under the axle.

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