Having spent a couple of decades in the retail car repair industry, I have seen some pretty crazy methods used to save money on cars, but this video takes the cake.
I can’t read the opening descriptions, but it would appear that this guy has sliced into the grooves of a worn out all season tire and then joined the resulting rubber tabs with tape. Then, the guy spins the tire and pulls the rubber strips out. He claims that this will extend the life of worn out tires by creating deeper grooves.
This might be one of the stupidest things I have seen.
Tires are designed to operate at a certain tread depth. That is why they have wear bars moulded into the tread grooves, to tell users when the tire is kaput. At that point, they are unsafe. Cutting beneath that increases the risk of nasty little things like blowouts! Don’t do it!
Update: Here is a longer version that shows new shoulder grooves being cut also. Thanks to Tommy and Kieran for the tip.