I ordered today a set of Centramatic Balancers.
Onboard Tire & Wheel Balance Systems, Tire Rotation, Tire Balance, Tire Balancing - Centramatic
I had searched here for some threads on the subject, and found the ones that turned up pretty much out of date....so here is an update.
I talked to Jerry at Centramatic. He knows his stuff. Centramatic has developed several different part numbers for fitting Airstreams. The one I needed was NOT in the online catalog.
They have different 300-556's depending on if you have drums or disc brakes, and if you have aluminum or steel wheels. It is important when you call to explain to the person answering the phone that you have an Airstream and need to talk to Jerry to get the correct part number shipped to you.
A set of four was $211.00. A longtime trailer owner friend of mine suggested I put them on because he has run them for YEARS and tows at fairly high speeds and once he put them on his 34 footer, everything quit shaking apart.
He always had his tires balanced and the hubs...as explained by Inland Andy, but the Centramatics work to keep the running gear in continuous balance.
Anyway, since most of the threads were of the 2004 era, and Centramatic had refined their product, if you want to consider Centramatic Wheel Balancers, be sure and talk to Jerry when you call them.
Once I get mine installed, and some miles on them, I will provide additional feedback.