This seems like something out of the 50’s. Tires are designed better every decade and some guy in a tire shop wants to redesign the tread? If he can show you a bulletin from the tire manufacturer reccomending this practice, go ahead and do it. (I think you and I both know he’s never gotten such a bulletin.) This is the weirdest sales gimmick/profit generator/money clip I’ve seen in a while. I’d really like to see you corner this guy as to whether the tire manufacturer reccomends this practice. By the way, what brand/model tire are we talking about here?