I have a set on my Bigfoot. My wheel/tires are well balanced but I wanted smooth. I do think they work but without putting instrumentation in the trailer before and after, I cannot prove it. The trailer tows like nothing is there on a good road.
Potential issues. The Centramatics have their tubes offset to one side of the flat center plate. In my case, the CM was not large enough to fit over the brake drum so the tube had to face outboard (ie: away from the drum, see the pics), and I had to be very careful to insure that it cleared the center hub of the wheel. Centramatic does not have any line drawings you can use to get dimensions, and were of no help at all when I called them. I ended up calling a reseller of the Centramatics, Texas Truck Supply or something like that. Anyhow, very helpful, they pulled the one I wanted out of stock and took a tape and gave me the ID and OD of the tube, and the max offset distance. The Airstream people are very fond of the Centramatics. My travel buddy put a set on his Ram 2500 and said you could feel a difference.
You really don't have much choice, standard 5 lug trailer is 5x4.5 (5x4½) bolt circle and that would be a p/n 200-221 (I have 6 lug wheels, so my p/n won't help you). This is where having actual dimensions would be helpful, there is a 300-345 that is punched for both 5x4.5 in, 5x5 in hole patterns and says for 16 to 20 inch wheels, which really doesn't tell you much. I think larger is more effective, and I probably could have gone to a larger one that also says it fits 16 to 20 inch wheels, but I didn't have the dimensions, the company I called didn't have a set on hand and Centramatic would not help me at all. Very poor customer service.
Also, be aware that many tire stores, especially chains like Discount Tire, will not install or reinstall any device like the Centramatics. You will do well to install them at home. I never take a trailer to the tire store, I jack the trailer and install jackstands and take the wheels in the truck.
Last pic is confusing to look at. Wheel is OFf the trailer and the centramatic is bolted to the back of the wheel with bolts and lug nuts to insure it lays flat on the back of the wheel and does not hit the wheel anywhere other than the mounting surface. I should have taken the pic with a piece of cardboard behind the wheel to eliminate the visual confusion.
The larger diameter CM could be turned so it sat over the brake drum, IF it cleared the inside of the wheel. Fog it with black paint and you would never know it is there.
https://centramatic.com/searchpagetst/?_sft_pa_wheel-category=trailers
https://centramatic.com/searchpagetst/?_sft_pa_wheel-category=light-duty
Charles