The rule with offsets is the lower the number the more it sticks out from the car. Pretty much the biggest wheel you can run with reasonable success is a 17 x 7.5" +43.

This link lets you compare two different rim widths or offsets: http://toy4two.home.mindspring.com/offset.html

If you enter in a 7.5" wheel with a +43 offset and a 7" wheel with a +38 offset you will see that the edge of the rim is 1 mm further away from the fender on the 7" wheel. So yes, it should fit.