i know they had allot of trouble with their 6x10 ultralites, no one can get tyres on them without tearing the bead on the tyre.
i had a set and trying different tyre fitters ended up with 4 scrapped yokos.
buy tyres from them, buy bits from them, dont buy wheels though!
I had the same problem with some 6x12's, its all because of the square edge of the rims.
I finally gave up and turned down and rounded off the edge on a lathe. Now tyres fit no problem.