For layouts with curves too small for full-length passenger cars, you need SCS's new "Selective Compression" series.
Recommended Parts
Wheels: 36" metal wheels with .54" (micro-trains) axles
Couplers: Micro-Trains #1023
Truck Screws: 2mmX4mm self threading, large head (Kato #900020, $1.00 for 6)