If you’re old enough, it does make sense.
During the war, rubber was rationed and most tires you could get were worthless retreads.
Good tires were a key part of a used car deal, and at times you would buy a wreck to get the tires.
There were few protections against worthless tires.
If you kick a few tires, it’s easy to spot the retreads. No-one actually does it any more, but at one time it was the smart thing to do.