After putting off installing a tire rack in my TPD trailer for too long I decided to follow Pegasus's advise and use E-Track and E-track 2x4 beam sockets to create a tire rack. The E-track system and 2x4 aluminum tubing (upgrade from wood) tire rack works great. The rack holds 2 sets of tires for my Formula Mazda making trailer loading process easy and looks cool. Only regret is that I did not do this sooner.
Fair Oaks, CA