285/55R20 vs 305/55R20

305/55R20 is 2.7% taller (+0.87 in) and 0.79 in wider than 285/55R20.

Close match

305/55R20 is 2.7% taller than 285/55R20. That is inside the ±3% most shops treat as a straight swap.

	285/55R20	305/55R20	Change
Diameter	32.34″	33.21″	+0.87″+2.7%
Width	11.22″	12.01″	+0.79″+7.0%
Sidewall	6.17″	6.60″	+0.43″+7.0%
Circumference	101.6″	104.3″	+2.7″+2.7%
Wheel	20″	20″	Same
Revs per mile	624	607	−16

285/55R20305/55R20

Change sizes Speedometer table Gearing

Speedometer shows 60 mph61.6mph

Real speed on 305/55R20.

Ground clearance+0.43in

Change in height under the axle.

Width per side+0.39in

On the same wheel, split inboard and outboard.

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285/55R20 or 305/55R20?

Can I use 305/55R20 instead of 285/55R20?

305/55R20 is 2.7% taller than 285/55R20. 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 61.6 mph if the speedometer was set up for 285/55R20. Going the other way, 285/55R20 would make it read 58.4 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.43 in (+11 mm) under the axle.

Other comparisons

255/55R20 vs 285/55R20 275/55R20 vs 285/55R20 285/55R20 vs 275/60R20 285/55R20 vs 275/65R20 285/50R20 vs 285/55R20 285/55R20 vs 295/55R20 285/55R20 vs 33x12.50R20 285/55R20 vs 295/60R20 285/55R20 vs 305/35R24 275/70R17 vs 285/55R20 285/55R20 vs 285/65R18 285/45R22 vs 285/55R20 285/55R20 vs 35x12.50R20 305/55R20 vs 285/75R17 275/70R18 vs 305/55R20 275/55R20 vs 305/55R20 275/60R20 vs 305/55R20 305/55R20 vs 275/65R20