Originally Posted by
CityRoamer
[snip]I am sure these do not have any leaks or tears[snip]
I'll take the contrarian view: in my experience, you're losing too much air too quickly. When you say that you're sure there are no leaks, what did you do to ascertain this? Did you submerge the inflated tubes in water and look for bubbles? Sometimes the problem is a leak at the valve stem; sometimes it's a very tiny pinhole leak, often hard to locate unless you do the water test.
And, meaning no disrespect, I'll also ask this question: assuming you have presta valves, you do screw shut the little valve cap or round nut after inflating your tires, right? Sometimes people simply forget to do this, and a slow leak results.