Mike- I just picked up two tubes Saturday. Couldn't get the 21-12-8 size either, ended up just using a 22-11-8 and it seemed to fill everything fine.
Let me know and I'll grab two more for you and I'll bring a set of tire spoons to the regatta and we can swap them out. I think they were about $6.
Is it that easy to put the tubes in?
Yep, took me longer to find the spoons, a pair of side cutters to cut off the valve stem, and remove the wheels than it did swap em out.
Those tires are stupid soft, the have no tread, a ton of sidewall and no load capacity. Just about as easy as they come.
