I weigh 200 lbs and my bike with batteries etc. weigh 70 lbs. and I've only had one flat in three years on my commuter bike that racks-up over 2,000 kms per year.

Don't purchase solid tires, nobody likes them for obvious reasons, just purchace good quality "shawalbe" (sp) tires about 1.75" or more inches dia. with good tubes and you will be comfortable and flat free. Get tires that are Kevlar or puncture resistant type. pay more now and save in the long run, including your sanity. Good luck