Measuring the P and R Dimension

Courtesy of GENERAL MOTORS COMPANY

Measurement Definitions 

P Height: The vertical distance from the ground to the top of the wheel opening through the center line of the front wheel (1).

R Height: The vertical distance from the ground to the top of the wheel opening through the center line of the rear wheel (2).

Use the following procedures to measure the P and R dimensions:

NOTE:

The left and right P and R height differences should be no more than 10 mm (.39 in).

1. Push the front bumper down a minimum of 25 mm (1 in), and release. Perform this step three times.
2. Measure and record the trim height per the "Measurement Definitions" above.
3. Lift the bumper up a minimum of 25 mm (1 in), and release. Perform this step three times.
4. Measure and record the trim height per the "Measurement Definitions" above.
5. The true P height measurement is the average of the measurements taken in step 2 and 4. Trim Height Specifications 
6. Repeat the above steps at the rear of the vehicle for the R heights.
7. See the trim height specifications for the modified R height measurement. Trim Height Specifications 
8. If the P and R heights are outside of the specifications, measure the Z and D heights.