Annie,
OMGosh, I can't believe you didn't pump up da tires. hehe. Keep them at max pressure. I think it's 60 lbs per sq in for mt bike tires. There's no way you can pop tires!! Most people don't know that bicycles can handle 500+ lbs, especially mountain bikes. They are over-engineered.
When you pump up your tires, you'll go faster and smoother! With them low, it's like riding through mud.
Hugs and luv,
Ratkitten

