[Illustration: SPREADER ROOM.]
The majority of automobile tires to-day are machine built, but there
are still a great many built by hand and this is the process we shall
describe first. In this process the books of fabric are laid up and
spliced into proper lengths to go around the tire and allow a proper
lapping for the splices. The proper number of these laid-up pieces,
or plies, as they are called, are placed together with cotton cloth
between and taken to the tire builder. The tire builder mounts the
core, upon which the tire is to be built, on the building stand,
generally cementing it so that the first ply of fabric will stick in
place. The first ply is then stretched onto the core and spliced,
rolled down with a hand roller onto the sides of the core, and trimmed
with a knife at the base. The following plies are put on and rolled
down in the same manner, the beads being put in at the proper time,
according to the size and the number of plies to be used. After all the
plies have been put onto the core the so-called cover rubber is put on.
This cover rubber is generally a sheet of rubber about one-sixteenth of
an inch thick or more, and of the same compound as the rubber on the
fabric.
[Illustration: HOW THE TREAD OF A TIRE IS MADE