I had Royal Tire here in the Minneapolis area install a new tire last week. It ended up leaking enough to go flat in a week. I took it in yesterday and they couldn't find anything wrong, but they replaced the valve core. I took it in again today as it was still leaking and they removed the tire. They found that the wheel was cracked at a weld. They had a reconditioned wheel that they put the tire on. The thing is they never charged me a penny for all the time they invested in finding the problem. They only charged me for the wheel.
It wasn't their fault the wheel cracked and I would have gladly paid the labor if they charged it. They have given me good service this year and last year with good tire prices.