My HO layout has grades up to 3% and I can't pull a decent cut of cars without some sort of rubber tires on a driver wheel on my Bachmann 2-6-0 Alco steam loco.  The loco wheels are all smooth with no groove to install rubber tire rings. Does anyone know of a source for driver wheelsets with axle that would have wheels with a groove that accept rubber tire rings?  I have tried putting rubber rings on the smooth rear driver axle wheels but in some curve areas a wheel with a rubber ring will go off track.