For laughs years ago I tried bolting my old Mustang's rear tires on the front of Focus_3XZ's Focus when it was stock. They were 26x10.5 M/T ET Streets mounted on 15x8 Bogart Racing Wheels with 5.5"bs. They just about fit, but due to the backspacing and stock struts the tires hit the spring perch. If they had less backspacing which would make the tires stick out more they would have cleared. Also, if he was running coil overs in the front with the spring perch removed they would have probably fit.
Here are the rear wheels and tires from my mustang that we fitted on his Focus a long time ago
Heres what I mean about running coil overs with the spring perch removed. BTW, the wheels and tires in this picture are NOT from my mustang. Read below for more info on them.
Now that Focus_3XZ's is no longer stock he had a custom set of Bogart Racing Wheels made specifically to his dimensions that are the perfect fit for a Focus. He is running 225/50R15 Hoosier Drag Radials mounted on 15x8 1/4" Bogart Racing Wheels with 6 3/4" bs. The 225/50R15 measure about 24" in diameter and are about 8 1/5" wide. The wheel tire combo fits perfectly without any modifications (no need for coilovers either) and the wheel can be turned lock to lock without any rubbing. They even fit on my SVTF over the large front brakes.