I will be running the weld pro starts 15x10 and 15x4's I will upgrade to the ARP studs, is there a certain length to get? Also... What style of lug nut will I need? And yes... I have the spacers for the front!

 

ProStars take what is refered to in the wheel biz as a "long shank, mag style" lug nut. Shank length is 1.310" and diameter is .682" +-. I would use an open end to ease tech inspection and to prevent the lugs from bottoming on the long studs before they are tight.