I'm about to purchase a set of DR17 with new tires, but they include the "valve stems", do I really need this or not? also, I can use my stock lug nuts right? thank you.

 

Are you asking if you need valve stems in general, or are you asking if you need to use their valve stems? Yes you need valve stems in general (duh), but as far as using the ones including, you don't have to... but might as well use the new ones they give you incase yours has a leak, or its worn etc.

Never use OEM lug nuts on aftermarket wheels. OEM lug nuts are ball seat shaped to fit OEM steelies, which mate with the ball seat lugs. Aftermarket wheels are acorn or tapered seat, so you need aftermarket lugs with acorn/tapered seats

Make sure you torque them to spec as well

Good luck!