I'm looking to get a pair of 18x10's for the rear and would like to buy some polished bullitt's that would match my factory ford ones. That way I only need to buy 2 rims and 2 tires. I've went to places like americanmuscle and tirerack and haven't found too much

Also, is there any reason to go wider on the fronts if I do have to buy all 4?

 

Don't think such a thing exists. About the only way you're going to do that with the factory polished Bullitts is one of the wheel shops that specializes in cutting aluminum wheels by cutting and rewelding them.

You're probably going to go with a slightly different style and a full set if you don't want to go to that extent.