At 12:55 AM 11/30/05, Greg Smith wrote:
>"I read your response with regard to applying silicone sealant to the spoke nipples, but I'm not so sure of its longevity and integrity. Do you have any experience with this?"

Yes. The wheel has to be VERY CLEAN for the silicone to adhere well. This is no problem with new wheels, but old rusty wheels would be a problem. When in doubt, have the inside of the rim abrasive blasted to strip it down to bare metal. Do not apply RTV over paint. For best results start with clean metal surface, dry and free of any solvents. Apply the appropriate RTV primer first to assure best bonding of the RTV. When done properly you may be able to adjust the spoke nipples without breaking the seal. There are several different primers suitable for bonding RTV to metals. See here: www.krayden.com/tds/dow_p5200_tds.pdf (176-KB pdf file)

Read the fine print in the instructions for silicone sealant, as they sometimes recommend a primer. If properly applied on bare metal with the right primer, the sealant is as good as vulcanized rubber (or maybe even better). If you put the silicone over dirty paint or rust, all bets are off.

You can ask British Wire Wheel for advice if you like. They will supply new Dayton Wire Wheels in tubeless form with the rims sealed in this manner. If I was using wire wheels, I would definitely clean them, seal them, and run tubeless. The advantages of running tubeless are numerous, not to mention the cost and bother of tubes. The last (and only) car I owned with tubes in the tires was a wire wheel MGA in 1968-1969. I know lots of people running tubeless on wire wheels, and have never heard a single complaint about leaks.

For the original 48-spoke wheels, all of the spoke nipples connect to the rim in the outboard tire bead area. The sealant has to stay below the bead surface within the pocket for the spoke nipple. This means each of the 48 points will be a separate rubber plug sealing an individual small pocket.

60-spoke wheels have 40 spokes from the inner hub flange going to the outboard rim bead and 20 spokes from the outer end of the hub going to the center well of the rim. This high angle crossover of the outer spokes to the center of the wheel is a much stiffer wheel design even if it wasn't for the additional spokes.

72 spoke wheels are built like 60's but with more spokes, 48 to the outer bead area and 24 to the center well. They also commonly have thicker spokes to make them lots stronger than the 60-spoke wheels. 72-spokes are good for aggressive driving with sticky race tires, but overkill for normal street radials. They also look rather heavy and busy for my taste.