Considering that a 285/65R18 tire is 11.22" wide, I would not suggest going under 9" rim width.

*EDIT* - do you remember what the rim specs where that you had them on originally?

 

swartlkk,
Not sure if I know the actual specs. But the BF's were put onto the factory wheels that came on the F-150 SuperCrew. And, again...based on your statement above...you are suggesting I stay with an 18x9 or more???

Scott

 

Well, I couldn't find a list for rims wider than 7.5", but on a 7.5" rim, it is not advisable to have a tire with a tread width more than +1.5" or 9" wide. Going with even a +2" width increase for rims 8" or wider would mean that 8" wide rims can take 10" wide tires, 9" - 11", 10" - 12".

I am also getting some conflicting information about stock F150 rims... Some say 18x7.5 and others say 18x9... Do you have a picture of what the rims looked like on that truck? The 18" stock tire size was 275/65R18 so an increase of 10mm on the tread width won't be much different, but it all depends on if it was a stock 7.5" wide rim or 9" wide...

Here's a thought. Since you have the tires in your garage, stand one up on its tread, then measure across the beads at the top. This should give you a very rough idea of what width rim it needs.