Tom

Dear    Tom,

Q I own a 2004 Cadillac Escalade, and there is a picture of the truck

displayed on the dash panel showing the left front tire only. What does this
picture mean?

Carolyn—Washington, D.C.

Carolyn,

A The tire pressure monitoring system detects low air pressure in the left

front tire. Check the tire with a pressure gauge, and compare the reading with
the other tires on the vehicle. I suspect you have a leak in that tire. A small
nail, a cracked valve stem, a bad valve stem core, or a rim bead leak can
causes a tire leak. Let’s assume that there’s no nail and the valve stem is
good. The only other possibility is a bead rim leak. This type of leak is
common on vehicles equipped with aluminum or alloy wheels. Water gets in
between the tire bead and bead seal area on the wheel. Corrosion sets up and
an air leak ensues. The best way to solve this problem is to clean the rim of
corrosion using a corrosive buffing wheel. Next, clean the tire bead area with
a tire solvent. Then apply tire glue to the rim bead area and inflate the tire.
The glue creates a moisture barrier and thus stops corrosion, and the tire leak
is fixed.

I have witnessed extreme examples of porous aluminum wheels that
leaked air in the body of the rim (due to poor casting of the aluminum or
alloy metal) and had to be replaced. Sometimes epoxy application can stop a
leak of this nature. I hope this helps.