Iron Mountain Road - Route 16A in Custer State Park SD

If you try it let me know ahead of time. I want to be there to video it. Should be good utube material.

NO WAY!

Two different official (State of South Dakota) sources list the tunnels thus:

Tunnel 1, 14' 0" wide by 12' 9" high (has bypass);
Tunnel 2, 13' 2" wide by 12' 2" high (has bypass);
Tunnel 3, 13' 4" wide by 12' 4" high.

Our rig is 11' at highest, which I'm calling 11'6" because, well, I'd hate to do without air conditioning. MH, not TT. No toad.

Somewhere I rea that direction of travel matters, because outside of tunnels there are overhangs on one side. But I forget which side.

Just came back from that area, was there last week. Don't take the rig on 16A. It's beautiful, but not fun for a TT. There are pigtail turns, not just switchbacks. A tunnel or 2 as well. Park the TT and then drive it!

I wouldn't do it in a large rig personally, there's some tight switchbacks that would be very hard to make with a large rig, I can hardly keep my Silverado between the lines on them, you may have to make some multi-point turns to get around them with a long rig. The tunnels are pretty tight, and would be beyond my comfort level for an RV, but I know people have done it and some tour buses do it regularly too (though they may be smaller than some RV rigs, so KNOW your measurements!), They post vehicle height/width restrictions at either end of the iron mountain road, so as long as you're within your comfort margin, go for it ;)

Sept 2014 video from one of the iron mountain tunnels in our Jeep

Not sure what road they are on in the park, but there are some tight tunnels and narrow places that our HHR was doing good to get through.
Edit: Looked back at map. Most of those are in the upper part, near Rushmore. Been several years since we were there.