"Seal the beads" - Leaking after the tire is inflated or getting the tire to pop onto the bead?
If it's the first, clean rust off the rim so it's smooth and some paint for rust control. If it still leaks, go with tubes. I don't know if it's marketing or not, but there are radial and bias tubes. Don't know if you have put tubes in before, but the first inflation is done without the tire valve in the stem. Fill the tube until the tire somewhat over inflated, let all the air out, put the valve in and inflate to the correct pressure. This will get rid of wrinkles which will kill the tube in no time.
For the second, smaller tire sidewalls are pretty stiff. I use plenty of lube and a tightened ratchet strap on the tread to force the bead against the rim.