Tomorrow will be my first time on stiff sidewalls, but I will tell you the standard wrinkle wall slicks are anything but stable once you get moving. Wouldn't hurt to double check alignment and bump steer, but I would venture a guess to say its probably just normal sidewall flex. I let my bro drive my car down the track once and it scared the crap out him on the top end. Get your hand on the chute lever! Lol