I run a fairly light car (Altered) with 17x33 tires & have run 14x32s on a 3800lb car. I've run tubes & no tubes but NEVER did I not "pin" the tires. As someone said, it only takes one time & you'll REALLY regret it. On both cars they seemed to react better, tires lasted longer and with no tubes the 60' was better. I've always indexed the screws, as mentioned previously, so the only conclusion/ question I can come up with is : For the small time & expense, why WOULDN'T you "pin" the slicks to the rims to avoid any potential problems when there's tons of evidence it actually helps?