Suspension Air bags

I went for the Firestone R4Tech kit. It totally replaces the rear suspension, and almost all the load (truck and trailer) is supported by the airbags. If I had it to do again, I would AVOID the R4tech kit. There are serious issues (clearance of the airbag to kit components) that had to be reworked by me and the installers to make it work. The next time I will put airbags, a viair compressor & small tank with pressure switch, and a auto leveling valve attached to the center of the axle feeding both airbags. The advantage of the r4tech is side to side leveling (for slide in campers) not needed with a trailer - as they all attach on the centerline of the truck. If you are going to make something yourself, get the largest diameter airbag that will fit. The larger it is, the lower pressure required to support the weight - lower pressure better ride.