Our car was November 2014 delivery. No problems until May 2015 when I found spare was flat, soap test revealed leaking valve stem which was only finger tight. Tightened nut - all OK and has been ever since. All other wheels were OK.
Then around Christmas discovered that one rear tyre was flat. Based on previous experience I tightened nut on valve stem and pumped tyre up. All OK since.
It looks as though there is an issue with how tight these nuts are at assembly and the amount of relaxation as the washers compress. I have now rechecked all 5 wheels and a couple moved a little bit.
