Disassembled one brake assembly and inventoried parts. Reviewed Matco manual. Coated tube with small amount of baby powder ( a little goes a long way!). Partially inflated tube and assembled wheel halves. Torqued wheel hardware to 100 in lbs. Inflated tube to about 11psi and noticed a leak (or what I thought was a leak) around the base of the valve stem when I deflected it to the side slightly. Didn't know if tube was leaking so I disassembled wheel and installed other tube. Tightened wheel nuts and inflated tube again. Same thing happened-- but it lessened and eventually stopped. I'm sure what happened was the air trapped inside the tire when the tube was inflated was escaping at the base of the valve stem- it's a tight seal around the bead of the tire.. I assembled the brake assembly and axle. Torqued wheel and disc hardware. Ready to assemble on gear leg. I brought first tube home to leak check in water and no leaks were noted.