Hey List,
I used RV antifreeze. I got it for about $3.00 a gallon, and I mixed it at about 50% RV Antifreeze 50% water. On the bottle it noted it was safe down to -50 degrees F, so I figured 50/50 mix should be pretty safe for me here in Colorado. I don't think I've ever seen colder than -10 ever here.
What I did:
1: set the valve stem at the top of the rim, let all the air out of the tire by pulling the center of the valve stem.
2: My rear rims have a large stem, that is held in by a nut and washer. I carefully removed the nut and washer.
3: I put a zip tie VERY tightly around the small end of the valve stem. This allowed me to poke the valve stem (tubeless) into the rim, and I held onto the exposed end of the ziptie with a vicegrip just in case.. I did NOT want to loose the valve into the tire of coarse.
4: I drilled a hole in a cap of the RV antifreeze bottle and put a hose through it.
5: Placed the hose into the large valve stem hole in the rim, and placed a jug onto the lid and then turned it upside down and poked a hole in the bottom of the jug for air flow.
6: Filled the rest of the tire up with water from the hose, I used some clear tubing slid into the hose etc to get the diameter of the hose small enough to fit in the rim hole.
6: Pulled the valve stem back out through the hole with the zip tie and replaced the nut and washer, and center of valve stem of coarse.
That's it, it seems to be OK so far (one day??)
Carry on,
Phill