Flynhi
Hello & Wlcome to the Forum!

I use: 2% slope for normal loco's
          4% slope for locos with traction tires
          6% slope for geared loco's, climax, heisler, etc. with traction tires.

Go slowly, keep your rise gentile so you don't break traction and experiment
with your locomotive to see what yours will climb. then try it with your cars attached
see if it will climb or just break traction.

Happy Rails.
dave