I've returned to my car twice in the last month to find tyres deflated. On the most recent occasion, both tyres on the driver side were completely deflated, and a locking wheel nut cover removed. It was also impossible to pump up the front driver side tyre again - it's not yet clear whether because of damage to the valve or tyre.
I've not had any similar problems with the tyres before, and different wheels have been involved each time. The tyre deflated in the first incident is still holding air, as is the rear tyre deflated this time. There are no obvious objects lodged inthe tyre, either.
It seems clear someone is doing this deliberately. Not only is this extremely annoying and time-consuming to fix, but is potentially dangerous if the tyres or valves have been damaged.
It would be useful and interesting to know if any of you have had similar problems recently, or have seen anything suspicious in the area.