Just purchased a new Spectrum 4-6-0 (Ma & Pa) w/DCC.  Great detail, runs smoothly and the motor appears to have adequate power.  I say appears, because on flat stretches it will pull as many cars as I choose.  However, it will not pull more than 3 32' freight cars on the grades without wheel slippage, and subsequent loss of traction.  My grades are all under 2 percent, with curves 22" radius.  I have two old Pocher 4-4-0 Americans which I have converted to DCC.  Both have vinyl driver tires on one side and will haul at least 8 - 10 cars up the grades.

The 10 wheeler does not have tires on the drivers, nor does it have any apparent way of installing them.  Any suggestions on how to improve traction on this loco, besides trying to add additional weight?

Thanks for your help.