My 98 v/6 has stock wheels in not real nice condition. 205-65-15 size. I am thinking of buying a set of wheels from a 2005 Mustang that has 225-65-16 tires. I believe the wheels will fit ok, and the offset is only 1/4 inch different, so I wouldn't think that would be a problem. I am wondering though if the larger diameter tire will be a problem? Not that it won't fit, but due to the fact of it gearing it up higher. According to a tire size calculator I found, they are about 1.5 inches taller, and will throw my speedo off some. Also with the low power 6 cylinder. would it be a problem for either the engine or trans? Automatic trans. of course.

 

1.5 inches is a lot, but I think you probably have clearance for that (Ford still designs these cars with clearance for tire chains)

the offset might be an issue with clearance on the inside (strut) or the outside (fender) depending on which way it is off, but like you say, you can probably get away with 1/4"

your overall effective gearing will be a bit "taller" than it is now; sort of like going to a 3.31 rear end ratio from 3.73 (not exactly but that is the idea) -- so acceleration generally will be a bit slower, but the transmission will compensate by running in a lower gear when needed

so overall I think it will be OK, but also hope someone else will chime in with more direct experience with those wheels on that car

 

Speedometer and odometer would be off as well.