Whats the biggest tire I can put on the rear stock fd wheels. I think right now it is a 245/50/16. Can I go any wider??? Also can I go any wider on the fronts???

 

245/45/16 is about the biggest you can safely put on the stock wheels. Check the suspension/wheels/tires section for aftermarket info.

 

Adam's suggestion is right. Installing a tire onto a rim that is narrower than the tire was designed for results in the sidewalls not being adequately supported due to their increasing angle from the rim lip. You will run the risk of handling problems and/or catastrophic air pressure loss if you try to work the tires hard. You will also probably run into problems with fender well/lip scraping, since the choices for 16-inch tire sizes are somewhat thin.