http://timeswv.com/local/x44818363/-A-lot-of-business
In that story, check out the 'related story' in the top right. Get a close look at the photo (it blows up large) and what they think will pull that truck with.
That photo was taken in downtown Fairmont, on a city street which has no markings for "no trucks", even though I have trouble pulling with my empty S-10 Blazer. Grade-wise, I'd say it's close to 12-14%. It's a good thing the road stopped him, because at the next intersection down the hill, the street he's on ends in a T, with a small cliff directly in front of him.