I had a wheel, with a brake drum bolted to the back of it, not on a car, and the bolts were done up extremely tight.
Normally, if the wheel was on a car then you would just use a breaker bar and some wd40.
But without the wheel on a car it was free to turn around as it pleased, even with me pushing it up against a wall with my knee or foot.

So, I went to the tyre shop and they couldnt get them off with their air tools.

Finally I worked out that all i needed to do was stop the wheel from turning and then i could use the breaker bar.

Solution: Chain the wheel to a tree, in one of the indentations between branches or roots.

After this the wheel could only turn slightly, after which it was stuck and i could apply enough force to get those bolts unstuck.

And the tyre shop said it wasnt possible!

Cool.
A few other tips are to soak the threads with kero, or some penetrating oil for a few days, weeks first.
Also put never seize or similar on the threads before assembly!

get some one to put their foot on the brake while you stand on a bit of pipe on the end of a breaker bar with the right size socket on it for the nut

You got it Barls, well said. I would have advised the same thing.

umm, no... the wheel was not on a car, just loose!
it was a front brake drum that was stuck on, i dont have any beetles with drum brake front ends, so there was no chance of putting it on a car to hold it!