on my mtn bike went up a paved road, sort of a private road, payroad, in Vermont where friends used to live with a tall lookout tower at the top, cant recallname, (will ask friends some time) and that was the steepest grade I'd ever gone up. With a 22-30 or 22-32, I couldnt go straight up as the front wheel lifted all the time.

when touring, had put a 24granny on for the Pyrenees trip, to go with the 30 rear (never really really needed it btw) but going downthe west coast, there were a few places in a Calif town the name I forget (nearish San Fransisco, maybe a day or so south) that had a nutso climb, very similiar but steeper than San Fran hills that I went on. The worst one had me in the 22-30 going as hard as I could and just barely making it up, but of course fully loaded so nothing compared to the video posted in this thread.

+2 on not liking to push a loaded touring bike, much easier to pedal IMO. I reluctently pushed my overloaded bike on some devilish sections on the Gaspe Peninsula trip, and it was murder. I do not like pushing a heavy bike, getting hit in the back of teh heels by pedals, grappling for traction. (granted, as I said, the bike was overloaded, I learned a lesson there, plus the gearing was only a 28 granny-30 rear, and the sections were badass)