You could try placing the inner tube inside the tire partially inflated. Use your tire levers to place tire back on wheel and do not attempt to push or pull the valve stem all the way in. Once you have the tire placed on the rim attempt to inflate by holding the valve stem between your fingers while inflating. Sometimes valve stems do not fit flush to the rim. You'll notice that the base of the valve stem is hard and rounded. By pushing the valve stem into the rim hole, you could be making the bulge prominent. Hope this helps!