If cars truly have trouble going up, you're looking at over a 30% grade. If a tractor trailer would be going under 15mph at the top, you *know* it's steep. They're paid to drive, and they tend to be quite good at squeezing speed out of their trucks in bad conditions. Lots of drivers don't know how to get up steep hills, so it depends some on your area.

But yes, I've gotten off and walked, even on just little rises and bumps. Sometimes your body says no . Nothing wrong with it. And well, if it really is over 30%, you're not a weenie. You're... normal. It takes a fair bit of strength and endurance to get up a 30% grade.