Ok like the topic says my rear wheels are rattling and it is very annoying. But it only happens when i have 2 people in the back seats or when I first start driving. It only happens on bumpy roads. In the begining I noticed the passenger side was rattling like a metal hitting a another piece of metal sound. Then the other night I had three other people in the car with me and both were rattling.:( The next day no noise, but I was by myself. Anyone know what to do or whats wrong? Also am I ok to still drive or is this doing anything bad to the car?

Thanks,
Chris