[Adrian E]

Originally Posted by MikkiJayne

Why not? I do the same...

Is it any different if they are mounted to wheels?

It depends on the volume - a pile of 4 won't be a problem, in practice, whether mounted or unmounted. A pile of unmounted over 1.6m high is a bad idea from a manual handling point of view, at the very least. They're designed to take load vertically (in the main) so by the time you've created a large pile, the ones at the bottom have quite a significant load being placed on the sidewalls, plus there's a risk of injury from the whole lot toppling over. If fitted to wheels you wouldn't want to go anywhere near that height, although the wheel and air pressure will reduce the likelihood of tyre damage.

It's been a number of years since I was involved with the tyre trade industry bodies that were working on best practice guidance, but for storage it basically recommends storing part worns for sale in the same way new tyres are stored (ie in racks, sitting on the tread)

This is for commercial retail, don't forget, rather than what you do as an individual storing your own stuff. I have a pile of 4 wheels stacked on top of each other. I just inflate them to a fairly high pressure before storing long term.