I get the standard thick rubber bike tubes, I go through about 3 or more sets a year because they never hold air.

I have to air them up every single time I ride.

Tire size is 28 x 1 3/8 x 1 5/8....thats what is has printed on the tires.

Everytime I get another set of tubes, I change brands. And so far, not one of them has kept air.

With all the money I've spent in tubes, I could just buy a nice set of solid tires or solid tubes, but I can't find any for this size.
They aren't getting punctures, I've checked them and had them checked. They just lose air every time I ride. And I ride on flat, concrete surfaces, so I shouldn't be having issues with punctures.