If you have tubeless beach wheels that are leaking or you can't get the tire to seal to the wheel, try adding a sealant made for tubeless mountain bike tires. This has worked for me on various beach and lawnmower tires. Some problems like hard to seal to the rim can be fixed with one application. Other issue will require that up refill the tires with sealant once or twice a year as the sealant dries up or is used up.

Right now my preferred sealant for big tires is Caffélatex. Next is Stan's. I don't use Slime especially on beach wheels because it has ammonia in it and can corrode aluminum wheels.

Trying this will cost you $10-25 depending on product and wheel size but if it works you can get a couple of extra years of life out of a set of wheels. This has extended the life of my original Rolleeze by 5 years.

There are some cases such as a damaged rim and tire bead where nothing short of a tube will work and the damage keeps poking a hole in the tube so you have nothing to lose. In cases like this SLIME makes some heavy SLIME filled tubes that will sometimes work.