What type of valving would I need to get on the bilstein 5150 with the 14" of travel, the 170/60 or 255/70, they're for the rear. I don't know what different sizes are for so if some one could help that would be great.

 

It depends on what you use your truck for. Do you tow, off road, etc. The higher the number the stiffer the shock.

 

I off road, jump, and hang my dirtbike off the back with a joe hauler but no major towing. Would it be best to go with the more stiff shock? I'm more concerned for juming

 

Most definitely go stiffer if you are jumping. If you find that that valving isn't stiff enough for you Bilstein can re-valve shocks to your desired needs. It's about $50 per shock.