Pro-Line HOW-TO: Upgrade Your TRX-4 [VIDEO] Trevor Duncan Featured News, Product News Comments From Pro-Line: Upgrade your Traxxas® TRX-4 with Pro-Line Shocks, Tires & Wheels! Do you have a Traxxas TRX-4? Pro-Line has some wheel and tire options for you as well as some shock replacements and scale accessories. Visit Prolineracing.com See more posts about Pro-Line Never miss an issue of RC Car Action! Subscribe today with a Digital Edition subscription or Print + Digital combo!