At Ease, Settle Down; Mike Slemmon gave me the answer this afternoon..........One side has an arrow and is marked 'front tire'-----the other side has an arrow pointed in the opposite direction and is marked 'rear tire' (which I initially missed seeing). Depending on what forces are exerted on the tread, front braking, rear propulsion etc. the tire is mounted in the direction noted by the arrow. So the tread points one way on the front wheel and the other way for the rear wheel. 19" tires are seldom seen on normal XLCHs so I overlooked it.
The main thing I learned today is that no matter what, Mike always has the answer for the most esoteric Sportster question.