19's will be perfect, the tires will NOT be extremely low profile. 05-07's have such large diameter tires from the factory. If you ran 255/40/19 on all four corners, you would have slighter less diameter than the stock tires. If you guys recall, 255/40's was a very common tire size for people to run on their 17's for the 87-93 Mustangs. The only problem is the that there does not seem to be many 19" options. I see many 18" and 20".