The strut problem is prevalent with 45 not 40 widths. This is the first I heard of 40's having a strut rub problem particularly 18". 18" isn't too big for the car scores of guys have them on. I am wondering, are the tires grossly overfilled with air? Even so, the 40's should give you plenty of clearance. That alignment checks out as ok.
Other than your struts being out of whack, the only other thing I can think of would be a balance problem on the front tires, but you'd feel it. Measure the width of the tire to confirm it is a 40?
