There must be a real risk of over-tightening the spinner if using a powerful electric drill. I have the Devil's own job undoing over-tightened spinners because of arthritis in my wrists (too much rugby!). I don't seem able to get my garage not to tighten them too much.

Part of the problem is that they self tighten as you drive. Painted wheels are more of a problem than stainless ones as the paint finish tends to “grab” the wheel nut / spinner.

I think that is what may have happened to my wheels, they may not have been off for years and had self tightened to the point that I would not have been able to get them off myself.

I had always understood that the spinner would tighten to the correct torque and not too much. Quote from MWS:

"Apply the spinner by hand and tighten 3 to 3½ turns; give the spinner a couple of taps with the hammer; lower the wheel to the ground and give the spinner a couple more taps.

As long as the hubs are fitted correctly then the spinners will self-tighten and lock as the car is driving.

If you hammer the spinners too enthusiastically then you will deform the thread of the spinner and the hub and they are more likely to work loose.

Over-tightening also means that if you ever need to replace either the hub or spinner then you will also need to replace the other part as the deformed thread of the old part will not fit with the new thread."

You would have to drive backwards very fast for a long way and using your brakes a lot for the spinners to undo.

Actually that’s a good question. The handbook recommends that you should re-tighten the wheelnuts every time you reverse the car.

Thanks for the heads up SFG, I must check mine when I get home tonight!

Actually It can be difficult to undo the wheel nuts if they’ve been on a while. A spray of warm water helps, which is why many Morgan owners keep a dog in the car

Damn that is what I am doing wrong.
Now I am back on wires they will be coming off once a year.