Tire Size

Bought a set of ralley wheels today. The fronts are 15x6 the rear are 15x8.5. I'm going with 275-60-15 on the rear. My question is what size tire do I need to go with on the front. Here is a picture of the wheels in the link. Thanks Rick

http://kansascity.craigslist.org/pts/2824055475.html