Incorrect trim height can cause bottoming out over bumps.
Incorrect trim  height can cause possible damage to the suspension components
    and symptoms  similar to those produced when there is a problem with the
   wheel  alignment.  Measure the trim height when diagnosing suspension complaints
   and  before checking  the wheel alignment.
Perform the following before measuring the trim height:
- Set the tire pressures to the pressure shown on the tire placard.
The tire placard is located on the driver's door lock pillar.
 
- Verify the tires match the tire size specifications shown on the
tire placard.
 
- Verify the wheels match the wheel size specifications shown on
the tire placard.
 
- Check the fuel level. Add additional weight if necessary in order
to simulate a full tank.
 
- Place the front seats in the full rearward position.
 
- Verify the rear compartment is empty except for the jack and the
weight simulating a full fuel tank.
 
- Verify the spare tire is on the spare tire carrier.
 
- Verify the vehicle is on a level surface, such as an alignment
rack.
 
- Close the hood.
 
- Close the doors.
 
- Close the rear door or the end gate.
 
- Verify the vehicle is not damaged from a collision.
 
Measuring the J Dimension
- Use your hands in order to lift the front bumper of the vehicle
up approximately 38 mm (1.5 in). Gently remove your hands in
    order to allow the vehicle to lower.
 
- Use your hands in order to push the front bumper of the vehicle
down approximately 38 mm (1.5 in). Remove your hands in order
    to allow the vehicle to rise.
 
Important: Measure all dimensions vertically.
- Measure the J dimension from the left and the right frame rail (1)
to the ground (2) 700 mm (27.56 in) from the front wheel
centerline (A dimension).
 
- Compare the measurement to the specification. Refer to 
Trim Height Specifications 
. If the J dimension
is not within 10 mm (0.4 in) of the specification, replace the
front springs. Refer to 
Front Coil Springs Replacement 
 in Front Suspension.
 
Measuring the K Dimension
- Use your hands in order to lift the rear bumper of the vehicle
up approximately 38 mm (1.5 in). Gently remove your hands in
    order to allow the vehicle to lower.
 
- Use your hands in order to push the front bumper of the vehicle
down approximately 38 mm (1.5 in). Remove your hands in order
    to allow the vehicle to rise.
 
Important: Measure all dimensions vertically.
- Measure the K dimension from the left and the right frame rail (1)
to the ground (2) 700 mm (27.56 in) from the rear wheel
centerline (B dimension).
 
- Compare the measurement to the specification. Refer to 
Trim Height Specifications 
. If the K dimension
is not within 10 mm (0.4 in) of the specification, replace the
rear springs. Refer to 
Coil Spring Replacement 
  in Rear Suspension.
 
Measuring the Z Dimension
 4WD Front Suspension Sectional View