Ask any decent Mercedes or any mechanic about pre-loading.....here's how I do it....I simply put the wheels back on and lower the car down onto a bunch of 4X4's while keeping some jack assistance..the lowering of the car onto its' haunches is sufficient..it allows everything to sit nice like. Then I go in and ratchet everything up...then you lift back up...remove the 4X4s or whatever, with the tires still on, lower the car via the jacks to the point where you can make sure the lugs are still tightened properly..if so (as it should be) drop the car and you should be good to go...there must enough room under there to do these things...are you sure your jacking the car up high enough?