I wanted to go on my weekend ride and realized that the rear tire was flat. I knew it had a slow leak but the tire was good enough to get to the station to get some air. I checked the tire for nails by spraying window cleaner onto it, I learned that at a Yamaha dealer; they found a nail in the tire that way. No nail or visible metal, I figured it must be the valve. When I pumped the tire with a hand pump, air was coming from the valve stem area. What bothers me is that there was a slow leak when I bought the bike (CRF250M) new in August '13. I kept the pressure up by checking once a week. At 6,000 km I changed the stock IRC to Michelins and had new tubes installed. 10,000 km later I had a slow leak again. Tire pressure would go from 30 PSI to 24 within a week. Couldn't have anything to do with a 140 instead of 130 rear tire? Today I ordered the third tube within 14 months/18,000 km. It takes ten days for the tube to arrive down here, then I have to take the bike in for a change. It's the same with the two Nouvo 135 I have; the one with mags doesn't need much air, only once a month. The one with spokes/tubes needs some air about every time I get gas - every 150km! Are there any high quality tubes I can order for the 250M? My next bike will definitely have mags!