I am installing 3/4" hardwood 3" strip over 3/4" plywood, mating up to an existing tile area. I have been told by an experience installer that I can install with the board ends against the tile with no gap. This worries me. I realize expansion is much less length-wise than width-wise, but NO expansion lengthwise? Any suggestions will certainly be appreciated.

The tree has been cut, dead and kiln dried. It is not going to grow any more. The way wood is and the cells that make up the tree, they will swell in the width, with a gain of moisture content.

Your installer is correct.

Thanks Floorguy. Good to have a confirmation.