I had previously replaced my left side outer CV joint and boot, (quite a drama), took the vehicle for a short run to determine it works OK. Great! Park the car. Job done. Today, a couple weeks after, it's a nice day for a longer drive and it's time for a run anyway. As is my habit I do a visual inspection of the tyres just in case of a slow leak. All going well, next thing to do is hit the tyres with a rubber mallet to get a rough indication of tyre pressure. I got to the left front tyre, hit the tyre - and the whole wheel moved! I have to admit not in a good frame of mind at that time. Jacked the car, pulled the wheel off, and a small stone fell off the hub, along with some mettle dust . Made mental note to in future always make sure the rear of the wheel where it is hard against the hub must be clean. Am now doubly certain checking the wheels before a trip is a pre-journey must. After the cussing I did manage to have a bit of a laugh.