This product has been fully endorsed by the NHTSA, the CDC and the American Society for Pimps. It was tested at -40F in NJ and high speed tested at the Nurburgring. The focus group's only concern was level of difficulty of installation. Hopefully someone else can chime in with a better set of instructions. I have personally placed an order for 3 diesel valcecaps (I really don't use all 4 wheels anyway).