Blaine07gt

will 19x9.5 rims with 245/45/19 tires fit 99-04 mustangs

Z28KLR

People stuff 20's under these cars all the time so I don't see why not. Worth considering though are the offset and backspacing measurements of those wheels (affects how they will "sit" - tucked in, sticking out a little, or just right) and whether or not the car is lowered and by how much.

Personally I wouldn't go any bigger than 18" on an SN95 for several reasons but it's your call, Chief.

I also think 245 is a bit on the skinny side for a 9.5" wide wheel, the sidewalls will be a bit stretched but they will fit. My section width of choice here would be somewhere in the 275-295 range.

school boy

The factory tire height is about 25.6 while the tire height of those are 27.6. That's going to push the tire about 1 inch into the fender well. You might get away with them depending on wheel offset and if youre lowered or not.