idk. thats the formula i found on a couple of websites. and mine were flush with the outside of my fender, and inside was about a 1/4 of a inch away from shock, had some rub on inside oftires from when i took corners to fast. i know my fronts were 225s, and i measured them to be about 9.5inches with a tape. my rear rims where 9.5's too, and i had major side wall slopes, my fronts were also 9.5s tho, and side wall was pretty flush with rim... ill see if i can get a pic up...

 

 

doesnt really show slope to well, and couldnt find a pic with readable tire writing. but those look bigger than 9s or 10s to me anyway.