If the tube you are looking for is 2.618” OD, yet the BT-80 is only 2.6" OD, you could consider adhering one or more layers of printer paper, or glossy paper, to the outside to increase the diameter by .018".

I've done that on special occasions. Spray adhesive on the tube and the paper works great.

To get the .018", you could use one wrap of paper that is 9 mil thick, which is in the range of photo printer paper, or a couple thicknesses of photocopy paper, which are around 4.5 mil thick.