What tires are you running? Mentioned many times in the past, stock tires are cheap soft junk. Ditch them then get a decent set of tires. Most new riders think stock junk is fine, it's not. Spend a little cash and get some good tires. Save yourself some haeartache.
Weight load will affect flat tires if you also have cheap stock rim liners. Spend five bucks and get that medical type tape liner (Velox). It is worth 10 times more when it comes to protection from spoke holes causing flats.