ok i got 2003 navi w/ 275-55-20 TSW wheels (don't think manufacturer makes any difference), at first did not have any problems but now air ride suspension is going crazy. sometimes car will not raise at all and it'll bounce like low rider. if the car raises i can put abt 4-5 fingers between tire and the wheel well but other times i can hardly put two fingers. if the car is parked and bags are empty sometimes it'll sag down to the point that i can't put pinky finger between wheel/wheel well and other times two fingers will fit. i've taken it to the lincon dealership and they worked on it 1st time and said nothing wrong w/ it but since is 2003 can't adjust ride height and since tires are oversized nothing they can do. 2nd time i took it in since it was pealing the tires while driving (it was that low) and again they've checked everything and again nothing they can do BUT offered to manually lift the car (rear only) for 300 bucks and adjust the ride hight when bags are empty so it'll stay half way up. it was all good for first few days and now back to the same problem where it'll lift between 2-5 fingers (so you can put your fist between tire and the fender/body) and when bags are empty/parked between 1/2 or pinky finger to height of 3 fingers. car is going back to the dealership again so they can work on in for the 3rd time. i don't know what else to do other than get set of 18" and original tires, and as a bonus if i do that it'll cost me again 300 bucks to lower it back to factory specs.

sorry about the book but don't know how to describe it in few words.

any word of advice is appreciated

pics were taken w/ cell camera so they are pretty crappy

My advice is to run a tire/wheel combo that is really close to 32 inches that is what the factory wheel/tire combo is. You can run as big a wheel as 24's w/o messing with the height of the vehicle just fine if the tires are not that big. I know of several cases where people have put 22 or bigger on there Navi's and had no problem, so a 20 should surely give you no grief. Measure the wheel/tire set you have and compare it to the factory 32.08 inches. Hope this helps!