9secondPhil use the M/T ET Street Radials, he found out that they have 1/2 the rubber left on the casing after the center tread is gone He would run them until the cords started showing, I did the same on my ET Street Radials and the my car ended up 60 footing better on a good track after the car got the tires worn in so the center grooves where gone He sent me some pictures of his on the side grooves, those tires would hook well until almost all of the side grooves where gone
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
He would run them until the cords started showing, I did the same on my ET Street Radials and the my car ended up 60 footing better on a good track after the car got the tires worn in so the center grooves where gone 
He sent me some pictures of his on the side grooves, those tires would hook well until almost all of the side grooves where gone 
