Well some people's WinRAR is not that good, so if the extracting does not work... and your on Version 38 like I am, I suggest moving to Version 37 because 37 is the best version for the trucks and stuff. I used to have 37, but uhh... yeah, I hated it. So, my suggestion is going to 37. You can find the Rigs of Rods Version 37 in Software.