Let me add to this thread by mentioning my own problems with these inflatable tires. Mine came with a 30% Paulistinha P-56. I was unable to inflate them with the inflation needle provided. I also disassembled the tire and the valve is a bit different. It's made of brass with an inner nut to keep it in place. The side of the inner barrel has a small pin-hole in it and is covered with a short length of silicon tubing.

http://www.rcuniverse.com/forum/rc-s...l#post11987430

At any rate, I've given up for now and ordered a set of solid 6" tires.