The wheels themselves won't rub. The only rubbing you have to worry about is the tire. Depending on width or sidewall height you may rub. But you would have the same problem regardless of 7 or 8" wheels.
If you are happy with the look of your current tires and just want to upgrade to a larger wheel try the following link. You can enter your current size and then plug in 16" sizes to match your overall diameter, tread width ...
http://www.1010tires.com/TireSizeCalculator.asp