check the tire for something in it. use a rag , run it in side and if it snug you found it, remove whatever it is. if the hole bother you can cover it with duct tape (inside of the tire ).check your valve it maybe lose. if you find the hole in the tube patch it, with a patch kit. if water doesn't work you can always hold the tube up to your face and feel the air leaving the tube or use soapy water and look for bubbles this goes for the valve too.you could add a liner for the tire too.