Antifreeze might break down and chemically attack the tire and rim.
Truckers have used sand, bb’s or other small objects.
There’s also ceramic beads made for his purpose that are supposed to be highly durable.
At some speed the liquid would “naturally balance” I suppose but in the real world of daily driving the liquid will at low speed remain at the bottom and as speed increases it will become a significant imbalance and can throw a front wheel up and down severely enough to be difficult to control. My experience with what appeared to be approximately 1 cup in a Ford Escort tire was that the car couldn’t exceed 45 mph as the wheel was becoming airborne by then. On a bubble balancer the liquid will be quite confusing. If the tire is set level on the pad and held there a few seconds it will center the bubble as if the tire is balanced. Tipping the tire would cause it to rock to the limit of the pad. Someone had installed several cans of Fix-a-Flat supposedly without the owners knowledge. The liquid had the appearance of anti-freeze. That was several years ago. I have since then seen a few other cars with liquid causing such a problem but immediately pulled the suspect wheel and dismounted the tire to check for liquid.
Living in a first world country and Walmart charging I think $4/tire when I had little money for car maintenance no.
Never thought about it.
@Meanjoe75fan … my 4WD truck has tire balancer gadgets based on the principle similar to what you propose. There’s one on each wheel. Has anyone else ever seen these things? A donut shaped thing, with holes to match the wheel studs, so it bolts right on with the wheel. The donut is hollow and seems to contain sand or something like that. The idea is the sand automatically distributes itself as the wheel spins I guess. I have no idea whether these gadgets do anything, but I’ve never had any wheel vibrations.
@db4690, that 1 hour for checking the balance on all new cars was not bad at all. Clean tires, no rust or mud, the balancer located nearby. I could do all 4 in 15-20 minutes without killing myself.
We did a lot of accessory work on pickups and we got paid well for it. An hour to add a chrome rear bumper, an hour for 2 West Coast mirrors, an hour for wheel well trim, etc, etc. None of those installs took more than 15 minutes.
I’ll stick with weights.
While on the road at Sturgis one year my buddy was having a subtle vibration problem due to a severely crashed bike several weeks before we had left OK.
The rear tire was showing some odd wear due to balance so we stopped on a gravel road turnoff in the Black Hills and balanced the rear tire with electrical tape and a rock from the road. We put the bike on the centerstand with the rear wheel elevated and ran it up in gear while stationary.
The size of the rock taped to a spoke was varied a few times until the vibration went away. Once back on the road it was smooth as glass.
The taped on rock was the best looking part of the crashed bike. A BMW club that came in from MN (slacks, loafers, and all) were giving scruffy us the evil eye until one of them just had to ask my buddy…
“Are you going to tell me you rode that thing all the way from OK?”. Yep, no problems at all other than that wheel balance/taped rock on the rear wheel.
At that point he just shook his head and walked off… 
LOL, that gives whole new meaning to the term “tape weight”.
Actually, that electrical tape weight stayed on there for the remaining life of the tire. It worked well so why tamper with success. Besides, a shiny new chrome motorcycle spoke weight would have looked out of place on that bike which looked like it had been dragged down 20 miles of gravel road.
It was probably the most beat-up BMW on the planet after surviving 3or 4 high speed crashes.
You would really get a laugh out of the repair methods used to get that thing going again the week before we left for Sturgis after the bike’s last crash sent it sliding through underbrush and small trees at 80+ MPH.
It always got from A to B with no problems though.
Floating a mounted tire,reminds me of an experience I had in the"joint" a fellow convict asked me to explain why things floated,I was trying to explain the laws of buoyancy and a shaved head redneck,chimed in and interrupted me saying"it floats because its full of air"so my experience indicates the myth about convicts being so smart isnt really that true.I always figured if those Guys were so bright,how come they kept coming back.But I suppose a lot of people have never heard of water displacement. And another thing I noticed was(IMO) the Guys who pretended they were in a second home,were predestined to comeback.My stay was enough to do me.I was real glad to ride away from that institute in my Wifes Honda Civic.
I was stupid enough onetime to think a relatively minor brush with Marijuana,would be overlooked or forgiven,boy they showed Me(,must have had a bad day or a quota)