I went through the whole thing years ago...it's a fair test IMO but it doesn't allow for anything else you've done to the vehicle to help bump it to different levels.
The way the tilt works is you drive up on this off camber thing:
(that one is the Asbury Park station, which is the one I'd recommend of the 3 if you can make the trek, *yes* a lot of things are left to the inspectors' discretion and unless things have changed since 2005 they're known the be the most lenient. this was also not always the case prior to 2005.)
Basically what they're measuring is the percentage of vehicle weight transfer to the downhill side...which is a measurement of how much your vehicle "tips". They weigh it level beforehand and then have you pull up on the ramp.
Another thing they'll ask you to do is to cut the wheel in a direction and then let go while driving forward, to make sure the wheels will still self-straighten - this is a way of checking that your caster angle isn't screwed up from the lift.
They'll also have you cut the wheel back & forth while watching the whole front end...I actually failed this the first time around due to a worn TRE that I wasn't aware of. Passed everything else (including the Home Depot garden-edge wheelwell flares and cutup-conveyor-belt mudflaps) and the guy who was in charge of inspections at the time (Dan Foley) had me come up to Asbury for the reinspection so he could train some new guys on my truck.
30" is actually a pretty generous door height considering what you can stuff under an XJ and still keep within that...most things on 33's and 35's shouldn't have a problem.
They put a sticker on your windshield that they write all your measurements on - including tire size - so if you put roller tires on it or load it up to squeak through and then change it after the fact, and get pulled over, if the cop measures stuff and it doesn't match you can get nailed for a reinspection.
That being said...*most* cops don't know or care and I went from this:
(yes I had flares & flaps on for inspection)
to this:
without getting hassled much or changing the sticker. But I could have.
Worth noting that in the second picture I'm still at 30" door height on 39.5s, just for reference, but would fail for many reasons if I actually tried to take it through again. :laugh:
Also worth noting that that second picture just made me kinda sad.