Scott & Sargeant may be able to help. You'll need to measure your existing tyre carefully - note the thickness as well as the width and purchase a length in excess of what you need.
I can recommend this
rubber-cork material - although, with the pot of glue as well, it does become a bit expensive. There are two benefits (that I can think of) in using this material over the standard rubber - one, you can 'cut' it with woodworking tools and, two; apparently, it won't dull the set on the "inside" of your saw blades... Or so, I've heard. Not that I've ever had that problem with this using conventional rubber tyres on any saw. Your average bandsaw blade is to be regarded as disposable, anyway.
If your saw is like mine and has a rectangular hole in the top, you could also use a plane blade in a honing guide to true the tyre:
I'd say this is the most difficult part of the job but, it is critical. Otherwise, your blades won't run true and you may find they appear to 'twist' while running. Also, you could find that, regardless of where you track the blade, it moves back and forth across the wheels edge. Bongo (a new member, here) has an image on his blog somewhere that shows you how to otherwise do this using a razor blade but
inside the saw. ;-)