315's will fit. 10" rims are a little narrow for a comfortable 315 fit if you're concerned about handling. The offset of your rims is most important, though - if you have the wrong offset, it won't fit. Measure carefully before you buy rims.
Corey either steve Jarvis or Andi is the right person to ask this q's regarding the tires. However there's no way u can put 315 on the rear without modifying the front inner frame rail and the outer fender wall! Andi is running that size but then again he's running,i think,11" wide wheel and had to do both mods.