I've been told an interesting tip. There are two variations on how you could fit it in, but both works the same. 1. Take an old tube, cut away the valve section. So it's like a long rubber tube now. Line this tube onto the inside of the tyre. Then fit the new tube in. Or... 2. Take an old tube, cut away the valve section. Then make a slit along the entire tube. Wrap it over the new tube, and fit it in the tyre. I haven't tried it yet, but I figure that option 2 would give sidewall protection than option 1. It should work like a downhill tube, as you're "increasing" the thickness of the tube.