Wheel Arch Height

Adjust the tire pressure to specifications.
Set the vehicle under "curb weight" conditions. (Empty luggage compartment, install spare tire, jack, service tools, and top up fuel tank.)
Set the steering wheel in a wheel-forward position.
Suspend a thread from wheel arch (point "A" in figure below) to determine the point directly above center of spindle.
Measure the distance between measuring point "A" and center of spindle.

Fig 1: Measuring Distance Between Measuring Point "A" & Center Of Spindle
Courtesy of SUBARU OF AMERICA, INC.

Fig 2: Wheel Arch Height Chart
Courtesy of SUBARU OF AMERICA, INC.