e55tom

While installing drag radials and wheels BFG DRs (275-35-18 Offset 40) on my 2012 E63 when lowering the car the fender edge touched the DR.

Not happy, I put the original tires and wheels 285-30-19 back on and noticed that the fenders were close to touching the tire but cleared.

The car was considerably lower.

After starting the car, it returned to its normal height and I had plenty of clearance with the stock tires.

Question: What controls the rear suspension? How does it decide to lower/raise itself and how much does the car squat under hard acceleration with drag radials. My concern is rubbing. Any help/ advice is appreciated.

lunarx

If it rubed lowered, it will eventually rub driving.
Same range of movement.
You should run 52 ofset wheels not 40.

e55tom

Thanks for your comments.

As I will not be running drag radials except for drag strip days can I take the chance that the car will raise itself after letting jack down and stay raised. In other words, does it only lower itself when jacking car up? If it will stay raised, the DRs will clear.

Anybody else have experience with the car raising and lowering when changing tires?

lunarx

It could be how you raised the car.
I lifted my car on the diff (with a wood block) and the car did not lower.
Its probably not the safest way to lift the car though.

How many inches of suspension drop did you see?

Im just saying its not a good idea to put a tire on a car that can rub when the suspension moves.
You cant be sure that range of movement wont take place while driving, especially racing.

e55tom

Raised the car with factory jack as I am waiting for my jack pads to come in.
Car lowered at least 2 inches.

Vic55

Par for the course--- when ever you lift the rear airmatic; once the raising device is removed the airmatic will be uninflated and it will sit in the lowest setting. YOu can either open one of the doors or start the car (if you are in it) and it will readjust the standard position.

Every time I swap wheels or raise the car this occurs and every time I open the door you will hear the airmatic suspension refill with series of air blowing noises. This does not occur up front since the 212's run springs now.

As for wheel rubbing, that would depend on your offsets and tire sizes (offsets are key). Squat will occur based mainly on your suspension settings- with comfort allowing the most squat.

e55tom

Vic...appreciate your expert comments. Learned much.
The owners manual not very helpful re this stuff.

At the lowest point the fender barely touched the DR. Do you think that I will be able to run these DRs at the normal suspension height under hard launch?

Trying to make these wheels and tires work rather than going through the return and reorder process. Of course, don't want to rip the fenders off of the car.

Vic55

Id need to see pics--- how much rubbing is really occurring? If its negligible Id probably keep it on. Are you lowered when the car is in normal position? I do not think, if you are not lowered, that you will rub since it will take a huge amount of down force to push the suspension down to the lowest point. The Airmatic and shock combo will hold it up even under squat. And even then with the squat- that will only occur for a short period of time during the launch.

otakki

Be careful since it has been asked and noted by the staff at the AMG driving academy that the rear differential is NOT a lift point. Of course, I really would like that lift location since it's easy to lift the entire end up.

Please let us know how the lifting goes. Are you planning to evenly lift the car up?...ie, lift from a central location and use the jack pads on stands.

e55tom

OK... thanks to Vic ( Appreciated all replys) I revisited my problem.

Jacked up rear driver's side of car using factory jack. Installed DR, released jack and car bottomed about 1/4 in from tire. Ditto on passenger side.

Started car up and car rose to standard height giving plenty of clearance for the DR. Took car for very careful test drive tried different suspension settings and transmission modes and always had plenty of clearance.

Yahoo...Englishtown here we come.