Who make a arbor for trueing foam tires. I need one for the Losi slider for dirt oval.

try this:
http://www.exotekracing.com/TEAM_EXOTEK/Entries/2007/11/17_MINI_ARBOR.html

I got one for my hudy truer and it will not extend far enough to reach the tire?

Go to a mill works store and get some taller hack saw blades or you can go to Harbor freight and purchase their big or large band saw blade. This blade is as thick as the Hudy factory cutters that come with your truerand should fit in you tool holder. Take a sharpe pair of cutters and cut the band saw blade into the pieces that will work for your truer. The band saw blade should be 1" wide, which should be enough to work on your wheels.

I got one for my hudy truer and it will not extend far enough to reach the tire?

Hudy makes an extended holder: http://www.hudy.net/xhudy/products/proddesc.php?prod_id=138&kategoria=151

who sells these? I have been to many websites but none list it? Is this a special order item? Thanks!