I use nothing but SanVal wheels on my cars. They work well on just about everything (Aristo, USA, Delton, LGB, Hartland, Bachmann) without modification. I got mine on eBay (seller ana.kramer). I have only used the solid axle ones (black or silver) which usually go for about $45/20 axles. They also have a ball bearing version which are more pricey of course.
-Brian
-Brian