I have tried soapy water, WD40, Armorall, etc.

I bought a bottle of Ruglyde recently....it works much better than the other stuff I have tried, and it claims in helps prevent rim slipping once the bead is set.

A gallon will last a lifetime as it takes very little....buy a bottle and split it up into pint/quart bottles with your friends.

http://www.autoparts2020.com/rsdev/part_detail.jsp?PART_HDR_ID=21945