Thank you very much for the input. I just saw that the tires were rated for 50-85psi, so I tried to fall somewhere in the middle. But I used a calculator and saw that I can/should go lower than that (same psi's you recommended), which will make me even more comfy.

I don't doubt the tube explosion was user error. I got reckless.

And I don't doubt walmart stuff is cheap. The tubes were an impulse buy and an unwillingness to accept defeat at 10:30 on a weeknight. I got a bicycle bell from there - not too worried about its quality. It works. I also got a water bottle and cage there that I'm happy with. I got some chain lube I'm happy with too. But I wouldn't buy any important parts from them.