I use the Meztler brand tube .My box is marked as this 19" Type A = 3.25/4.10, 110/80 to 130/80, 100/90, 110/90.. Known as Metzeler ME-E 19 M/C
I just went to my closet and grabbed a new tube to check. This tube will ''only work with a extra wide rim'' Such as the Large marge. If you actually ran into a tube rated just a bit less girthy?
On a wide rim this tube fits and I mean just fits. They are in my opinion a match made in heaven!!
You air it up and it is hella thick! Thicker than a good many other so called heavy duty tubes. I don't think one can make this fit with a narrow rim combination tho.
Sportscarpat is right the mountain bikes tubes are generally just as thick. Just cannot find them in 24x3.0
I had a 87-5955 tube 70/100 -19 This gets you here.
http://www.speedsupplies.com/accessorylistingdetailpurch.asp?item=20699 but sadly it was a tad too small. It was however a freaky thick tube. Thicker than anything I ever saw in any bicycle tube ever. For a narrow rim set I would look for a tube just a hair bigger in girth? If I was to go that rout again.
That is as far as I got.