What is the math to figure out what width tires to put on what width rims?

 

depends on offset and if it is for the front or rear. if those are the rears a 245 or 255 would be best. as for me, i have an 8.5 up front and run a 225 to get a little stretch and have more clearance.

 

yea im running 255 on a 8.5 +48 which required some fender chopping and bumper mods...not really worth it tho, id go with a 245 if you dont absolutely NEED the extra rubber

 

If you got the offset of the wheels I could tell what would be the best size. If you are willing to do some modification then it really would not matter as much. You can run as big as 255/40R17 in the rear and a 225/45R17 in the front.