Howie, did you ever figure out why you were getting all those flat tires ? Most of us were running those heavy natural rubber inner tubes back in those days. We had a lot more flats with the big Drag 500s - wheel spun inside tire - screws were a joke and not effective. Then came the big Hoosiers sprint car tires . The beads were too big and not tight to the wheel (lots of flats with inner tubes). Then came beadlock wheels and no tubes but the early Hoosier tires leaked thru the sidewalls like a sieve. Lots of compromise in those days between running low air pressure (car ran faster) and running higher air pressure in an effort to finish races.