No problem. I don't know anything about folding bikes, but I ahve a Specialized hybrid and a Diamondback Mtn. Bike and both of them work fine for me.

I'm not beating around the bush here, we are big people, and so we do have to make some adjustments. You will have to watch the tire pressure when you are riding at first. Check them as often as you think you need to while riding. You'll probably do it alot at first, then less over time as you gain more confidence and more knowledge of the equipment and how it performs. Keep a rack-mounted pump with you, and do some shorter rides near your home. Get comfortable and then hit the road. No one will care that you stop every now and then to pinch the tires.

For city riding, I much prefer a hybrid. You should be able to get a hybrid, and have the bike shop put on Mtn. Bike wheels and tires it, if you don't mind the extra expense.

I haven't bought a bike in years, so do some research, do some google searches for reviews of bikes. Don't buy a bike at Sears or Wal-Mart. Go to a real bike shop, near your home and see what you can find.