So I take care of the 92 crown car and before I was the crew chief on it I was the tire guy. As far back as my notes show, pretty much every pavement race I only buy 1 set of new tires and have a second set of scuff tires that I practice on. I also am the crew chief on the 7x RMS midget and take care of all the tires for the whole team. Your stagger will vary a 1/4" on pavement if you have a good baseline. On dirt your stagger can change 3" or more a night so you have to have enough tires mounted to do that.