305/55R20 vs 285/75R17
285/75R17 is 1.9% taller (+0.62 in) and 0.79 in narrower than 305/55R20.
285/75R17 is 1.9% taller than 305/55R20. That is inside the ±3% most shops treat as a straight swap.
Real speed on 285/75R17.
Change in height under the axle.
On the same wheel, split inboard and outboard.
Shop 285/75R17 tires
Opens the store’s own searchPrices and stock change often, so check a few stores. We don’t earn anything from these links.
305/55R20 or 285/75R17?
Can I use 285/75R17 instead of 305/55R20?
285/75R17 is 1.9% taller than 305/55R20. 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 285/75R17 you are really doing 61.1 mph if the speedometer was set up for 305/55R20. Going the other way, 305/55R20 would make it read 58.9 mph at a real 60.
How much ground clearance does it change?
Half the diameter difference: +0.31 in (+8 mm) under the axle.