What is your rim width?
What is your dual spacing now?
What are the recommended rim widths for the tires you want (find out from the tire manufacturer)?
What is the minimum dual spacing for those tires?
Make your comparisons and decide.
For a guide and general info check the Accuride wheel catalog, they have a couple pages on this stuff.
A link to the catalog can be found in this tech tip
http://www.stovebolt.com/techtips/wheels/Grigg