Knocking? that's the first time I heard that,in regards to tires/rims.245/45/R17 is factory tire size.The shop is full of ***** saying it's because of low tread.Give me a break.The crap they will say to get your money.They are just trying to sell him a new set of tires.It will NOT fix the problem.
I noticed those rims are 9".Perhaps the offset on them is causing a rubbing issue,particularly the drivers side tire rubbing the swaybar at full turn.I have a set of 06 GT wheels on my 96.The ones with the pony/5 lug center cap.They rub at full turn,even with 1/4 inch spacers.Doesn't get near the fenders though.
It's either that or he has suspension issues.Jman,you had them on your stang.Did you ever have any problems with those rims/tires rubbing?