I have had three tyres blow out on my trolley since I started, two of them blew out good style, scared the brown stuff out of me, it really sounded like a rifle shot. Northern tool no longer sell the tyres on their own, you have to buy the wheels, about £8 each if I remember right, you used to be able to buy the tyres for a quid.
These tyres are supposed to be rated for 30PSI, the ones that blew out on me were nowhere near that.