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98 ILLUSTRATED WORLD
"THERE is a popular notion among motorists
that tires will become overinflated on hot
summer days from the expansion of the air by
heat. So they very carefully see that the pressure
in them is reduced on such days from
five to ten pounds. When it is remembered
that heat does expand air this conclusion is a
perfectly natural one, but the fact of the matter
is that the increase in pressure from this cause
even in the hottest weather is so slight that it
is barely perceptible on the gage. When a
figure like five to ten pounds is allowed the
tires will be under-inflated. This is a greater
cause of damage to them than hot weather
expansion possibly could be. The proper pressure
is the one recommended by the manufacturers
and which is usually marked on the tires
when they are sold. At that pressure the tires
will "stand up round" without any passengers
in the car. One of the tire companies sells a
gage in the form of a caliper and this is said
to be more accurate than the sort which registers
in pounds per square inch, since it is seldom
that there are two of the latter sort in
accord with each other. The caliper is placed
over the top of the wheel so its two points will
hug the sides of the tire. It is then placed
over the rim of the wheel at the bottom so the
points can slip over the sides of the tire there
too. The points should clear both sides of the
tire at the bottom with the same adjustment
as at the top. If they will not pass it shows
that the tire bulges at the bottom and is therefore
insufficiently inflated.
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VT7HEN the engine has been standing a long
time in a cool room it is often so hard
to start that it tries the patience of any man.
An expedient that has seldom failed in such a
case is to remove some or all of the spark plugs,
invert them and fill them with gasoline and set
fire to them. When the gasoline has burned
out the plugs will be hot. Replace them in the
cylinders before they cool. If there is nothing
besides the cold preventing the engine from
starting it will now fire without difficulty.
* * *
]W[IX a quantity of soapstone in gasoline
and add a little glue or cement, and paint
the inside of the wheel rims with it. The tires
will then come off and go on with ease.