Here is a tip for you if you are getting your wheels balanced, insist they use the stick on ones if you have alloys, my brother is a retired car mechanic told me that the weights that clip onto the rim chips off the protective lacquer, this over a period of time causes corrosion with water and the two different metals next to each other. As the corrosion sets in it breaks the seal from the tyre and the wheel, which makes the tyre slowly lose air over a period of time. This also applies to car tyres with alloys.