The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. A tire graded 200 would last twice as long on the government test course under specified test conditions as one graded 100.
Most wine racks are designed to allow a wine to be stored on its side. The thinking behind this orientation is that the cork is more likely to stay moist and not dry out if it is kept in constant contact with the wine. Some wineries package their wines upside down in the box for much the same reason.
Since the milk solids can settle to the bottom, be sure to turn stored cans upside down every few weeks and use within six months. My grandmother used to have a gadget that fit snugly over the top of the can like a lid and automatically punched opposing holes in the top of the milk can.