28" Tire to rocker clearance - Duster

I have 28 inch tires on my dart. It was close when installed them but I thought it was okay. At around 105 MPH the tire grew enough to rub slightly. These are MT drag radials by the way. I then made a spacer to move my rear end back. I too have the MP offset spring hangers. After the small spacer I am now good to 120 MPH with no rub and that is as fast as this dart will go for now. Hope this helps.

I appreciate everyone's input - lots of helpful feedback.

This is a 275-60R15 (28.06") Cooper Cobra, Espo 1" over springs in stock location on Crager 15x8 with 4.25" backspace.
Sorry,car is on stands at the moment so no precise measurement. Hope it helps!