There used to be a huge 'post pics of your wheels with measurement' thread. Can't seem to find it now. 
 
	 
 
	Generally, with stock or slightly rolled fenders, you'll want to be somewhere in a 15x7, 15x8, 16x7, or 16x8 with a 0 offset. 
 
	 
 
	If you're willing to cut your fenders and add flares, you open up a lot of options for wider wheel and tire combos.