We are taking our first long trip and I need some advice about driving in the mountains. We are making our way from Fort Myers, FL to Cincinnati via Hilton Head. (It is so nice here in Hilton Head it is hard to leave.)

From Fort Myers to Hilton, the hills are mostly overpasses. From Hilton Head to Cincinnati the hills get larger.

I assume going up hills is just stand on the gas pedal and let it do its thing.

I'm more concerned about coming down. We are in an H3-45 with transmission retarder (no jake brake) and towing a 4,500 lb car. How do I determine how far to downshift and how much retarder to use? I realize the size of the hill really matters so I guess I'm looking for general advice.

Thanks for your help.

Terry