Let's start with sealant. You can either buy sealant (Stan's NoTubes makes good stuff), or you can make your own for about 1/10th the cost. Go to a hardware store and buy some latex additive, or an art store and buy some liquid latex. Either will work.
For homemade sealant, mid together:
- 4 parts latex
- 1 part windshield wiper fluid (lasts longer than water, doesn't freeze in winter)
- A bunch of glitter (weird, I know. It fills bigger holes really well)
Making your rims air tight is the next challenge. You will need the following materials and tools to finish the job:
- 1 roll electrical tape
- 1 roll 3m filament tape, in a width that will fit in your rim
- scissors
- Air compressor or CO2 cartridges, Flash-esque pumping skills.
- an old tube with a threaded valve. Best option is something with a removable valve core for adding more sealant later. Don't use road tubes, the rubber is too thin and won't create a good seal. Make sure you have the little nut that threads onto the valve.
Start by removing whatever rim strip you have, and clean the inside if your rim thoroughly. Next, begin wrapping the filament tape around the inside of the rim, starting near the valve hole. The number of times you go around depends on the depth of your rim. A deeper rim needs more tape. Usually, 3-5 times around is good. You want to raise the bed of the rim up so that the tire beads sit closer to the bead hooks of the rim, making inflation much easier. If you look at the NoTubes rim strips, they raise the rim bed up quite a bit. You want to do the same thing with the tape.
Once you have a bunch of filament tape on the rim bed, switch to the electrical tape. Go around the rim twice, trying to cover all of the filament tape. This is to a provide a smooth rim bed, and to protect the filament tape from the sealant.
Poke out the valve hole. Don't bother opening it up very much, just enough for the valve to get through.
Take your flat tube and cut the valve out. The piece of rubber attached to the end of the valve should be about the size of a nickel.
Stick the valve into the rim about half way, so that the rubber on the end is NOT sitting in the rim bed. You need to be able to fit the rim beads in between the valve rubber and the rim.
Grab your preferred tire. The tire can tubeless ready or just a standard tire. Tubeless tires will mount up much easier, but they are heavier. Standard tires often take a bit of coaxing, and sometimes (rarely) won't work at all. A tire that has been mounted before will air up much easier than a brand new tire, because new tires usually still have creases in the bead from being folded. These creases let a lot of air out. So, if you can, mount up a new tire with a tube for a few days before trying to make it tubeless.
Mount up one bead of the tire. Make sure the bead sits in between the rim and the valve rubber. Remember, the valve shouldn't be pushed all the way in yet.
Begin mounting the second bead, starting at the valve. Again, put the bead in between the valve rubber and the rim. Work your way around the bead, but leave a bit open at the bottom so you can pour the sealant in.
Pull the valve all the way down, put the nut on and tighten as much as you can by hand. Then take some pliers and tighten until the pliers start to slip on the nut. Very tight. You have to press the valve rubber into the valve hole of the rim.
Grab your bottle of sealant, and shake vigorously. You have to get the latex all spread around.
Pour the sealant into the tire. 1 cup is enough for more tires. More for bigger tires, less for smaller ones. More for thin tires, less for tubeless-specific tires. Spin the tire so that the part of the bead that is not mounted is at the top, then finish pushing the bead on.
Grab the wheel by the hub and spin, shaking up and down. Try to get the sealant all over the inside of the tire. Some may dribble out the sides - that's fine.
Use an air compressor or CO2 cartridge to inflate the tire. Air compressors work well and are cheaper, but you may need the quick blast of air from a CO2 to get the tire to air up.
Once you get some air in the tire, and it seems to be staying, grab the wheel by the hub again and spin and shake. There may be bubbles and ooze coming out the sidewalls - try to get the sealant to hit all these points until they stop bubbling and oozing. Grab your pump, and reinflate to 35-40psi. Lay the wheel on its side (the top of a trashcan or bucket works well for getting it level) and leave it there for a few minutes, then flip it over. Repeat until oozing stops.
Go for a quick ride around the block, bouncing up and down as much as you can. Again, you want to the sealant to fill up all the tiny holes in the tire.
You're DONE! The tire may deflate the first night or two - just pump it up before even touching it. If you accidentally push the bead off the rim, you'll have to use the compressor again. Sad day, that.