Ok my truck currently has 275/60/20 and I was looking to get some new rims with some 305/55/20 which are 33 inch tire.. But if my math is correct..

60% of 275mm = 6.496 inches.. So that means my current tires are 33 inch tires right ??

I mean the 55% 0f 305mm = 6.064 so there for the new tires are 33 inche tires..

So there for what would be the advantages of getting new tires if they are already 33 inch tires, is it just the nitto terra grapplers are more aggresive looking or what ?

 

Mainly width. The 275/60/20 tire is 33" x 10.8" and the 305/55/20 is a 33.2" x 12" tire...