For the rear you adjust the spring.
To raise the rear loosen the upper blue ring with the smaller wrench and then tighten the the lower ring with the large wrench. Then Tighten the small ring against the large.
It'll compress the spring but the overall length of spring and perch will be longer,
*EDIT*
Figured I'd include a picture for your consideration.
Measured from floor of garage to bottom of wheel-well lip across the wheel's center cap. Front is at 29" and 29 3/8" in rear.
Stock the front was 29 5/8" and 31" in the rear.