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Checking PSI and Reading Tire Wear

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					Checking PSI and Reading
       Tire Wear




                           1
Air Pressure:

The tire and rim assembly is an air chamber,
which supports the weight of the vehicle.

- air pressure supports 95% of the
  vehicle weight.

- the tire just 5%

- inflation is critical part of the tires
  ability to perform.

                                               2
Pressure:
Underinflation is the #1 enemy
  - causes tire stress
  - irregular wear
  - loss of control
  - a tire looses up to 1 psi per month
  - can loose half of its pressure and not
    appear flat.
  - psi is specified by vehicle manufacturer and is
    shown on the door edge, door post, glove box door
    or fuel door and in the owners manual.
  - check air pressure when tires are cool not hot.
    PSI rises 1-2 lbs for every 10 degrees of temerature.
  - visually inspect tires for objects embedded in the
    tread leading to air leaks, also check sidewalls for
    gouges, cuts, bulges or other irregularities.
                                                            3
Alignment:
 Misalignment of wheels in the front or rear     can cause
 uneven and rapid treadwear.

 An indication of trouble is “pulling” or vibration.

 Front wheel drive and IRS, require alignment of all four
 wheels.

 Tire dealers should check caster, camber, toe-in and
 wheel balance




                                                             4
Rotation:
-Promotes uniform tire wear.

-Each tire supports a different amount of    weight, this
 unusual weight causes tire to wear at different rates.

-sometimes front and rear tires use different pressures,
 always check.

-Tire Pressure Monitoring System (TPMS) warns drivers
  when tires are 25% underinflated




                                                            5
Tread:
 When tread is worn down to 2/32nds of an inch
 the tire must be replaced.

  Some tires have “wear bars” (small raised bars of
  rubber in the groove) If tread is even with “wear bars”
  it’s time for a new tire.

  If a tread depth guage is no available a penny is a
  reliable way to check tire tread, place the penny in the
  tread groove upside down, if you can see all of Lincoln’s
  head replace the tire.




                                                            6
Reading Tire Wear:

 The way your tires wear is a good
 indicator of other parts of the
 suspension. Abnormal wear patterns
 are often caused by lack of tire
 maintenance, or front end alignment.




                                        7
Overinflaion:

  If your tires are overinflated by 6 psi, they could be
  damaged more easily when running over potholes or
  debris in the road. They will ride harsher but
  responsiveness will improve to a point.

  Tire pressure must be checked with a quality air gauge,
  it cannot be estimated through a visual check.




                                                            8
Over-Inflation: Excessive wear at the
 center of the tread indicates that the
 air pressure in the tire is consistently
 too high. The tire is riding on the
 center of the tread and wearing it
 prematurely.




                                       9
Under-Inflation: This type of wear
 usually results from consistent
 under-inflation. When a tire is
 under-inflated, there is too much
 contact with the road by the outer
 treads, which wear prematurely. If
 the psi is correct, a bent or worn
 steering component or the need
 for wheel alignment could be
 indicated.


                                  10
11
One-Sided Wear: When an inner or
 outer rib wears faster than the rest
 of the tire, the need for wheel
 alignment is indicated. There is
 excessive camber in the front
 suspension, causing the wheel to
 lean too much putting excessive
 load on one side of the tire.
 Misalignment could also be due to
 sagging springs, worn ball joints,
 or worn control arm bushings.
                                    12
13
Second-Rib Wear: This is usually
 found only in radial tires, and
 appears where the steel belts end
 in relation to the tread. It can be
 kept to a minimum by paying
 careful attention to tire pressure
 and frequently rotating the tires.




                                       14
Check for understanding:
1. What are three causes of uneven
   tire wear?
2. What supports the weight of your
   vehicle?
3. Why is tire pressure checked
   periodically?
4. How is tire pressure checked?
5. What are some of the capabilities
   considered when selecting tires?
6. What is the effect of low tire
   pressure?
                                       15

				
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posted:9/5/2011
language:English
pages:15