BMW M5 Forum and M6 Forums banner

1 - 16 of 16 Posts

·
Registered
Joined
·
2,380 Posts
Discussion Starter #1
I knew I was in need of new rubber already and was getting ready to order a new set...most likely pilot PS4s to replace these PIlot super sports unless someone can convince me otherwise). Today during my oil change I noticed the rear passenger is down to the belts. Is this normal wear for these cars? Or does it need looked at before putting new rubber on? Thoughts?

rear wheel setup is BBS 20” wheels that are 22 ET 20x9.5 + 5mm spacer running 285/30/20

Rear passenger
937176



Rear driver...not quite down to the belts but you can see the low spot on the inner shoulder where it has the bald spot in the tread line

937177
 

·
Registered
Joined
·
410 Posts
This is classic wear due to excessive negative camber. You probably are running at least -2 degrees or likely more. when you look at the car from the rear can you visibly notice the top of the tire leaning in (vs the bottom). Adding offset spacers only makes the effect worse. Rear toe is also adjustable but you must fix camber first as it affects toe.
 

·
Registered
Joined
·
2,380 Posts
Discussion Starter #4
I’ll check looking from the rear....are you saying to look at the stance while it is on the ground?

it’s stock whatever it is....I’ve never messed with the suspension on it and neither had the 1 prev owner.

I just checked the fronts and even they have the slight extra wear on the inside shoulder like the rear driver side. I guess it’s not horrible as the tires are down to the wear bars and are in need of replacing anyway.

did I read the Michelin PS4 are slightly wider than the Michelin PSS?
 

·
Registered
Joined
·
410 Posts
The alignment will drift and change over time and especially on rough roads or impacts with curbs, speed bumps, etc. You need an alignment check for sure for the rear, but also the front. The wear on the fronts on the inside shoulders is normal, the measurement is what matters. The prior owner could have had the car set up for -2.5 deg, which is agressive for normal street use.

The spec for rear camber according to my alignment machine is -1.67 deg. The software says for the front it is -1.25 deg. There are more performance oriented settings for camber that go out to -3 deg. That will cause inner shoulder wear in a no time at all but those of us that run such high negative camber are running at the track and will go through a set of tires quickly because of that. I think others have posted the factory alignment specs here on the board.

I was just doing my own alignment earlier this week as I replaced all the front control arms and tie rod ends in conjunction with removing the front subframe. I'm using a Hoffman which is the same as a John Beam and Snap On. My front left had shoulder wear on the outside and normal on inside. The pre-alignment measurement said I had +1.53 deg of camber which is way out of spec but matches exactly the tire wear pattern. There is a removable pin on the front which is pegs the camber to a specific value from the factory, it was still there. I've only put on like 2k miles since I got this car 2 years ago, but the alignment had been off for a long time (I could have checked a year ago but been busy with other stuff). The pin can be removed with 3mm hex to adjust. I'm still waiting for the special tool to arrive to allow me to crank the top of the strut tower in adjust it in.
 

·
Registered
Joined
·
410 Posts
I’ll check looking from the rear....are you saying to look at the stance while it is on the ground?
yes. you can eyeball. You can take a simple house hold level or a string with a rock tie to the end. use that as a reference of pure vertical. compare the distance from vertical at the bottom of the wheel vs. the top. 2 degrees will be noticable.
 

·
Registered
Joined
·
2,380 Posts
Discussion Starter #7
Since I’ll be getting new rubber and I have low tech front springs I could get it all put on at same time and get an alignment.

one thing I have noticed for quite a while is I get a rubbing sound...sounds like its coming from the rear when I turn on to street that is not even with the street I’m on...for example I turn onto a side street go up a slight grade. It sounds a bit like tire rub on the fender but I’m not close enough to rub there.
 

·
Registered
Joined
·
410 Posts
If it’s grunt noise when you make a tight turn right, it’s likely the differential plates slipping. It’s normal, you can put in a different diff fluid to make it go away if it really bugs you.
 

·
Registered
Joined
·
2,380 Posts
Discussion Starter #9
You might be on to something...would it only happen with a turn to the right though? And does it have to be steering all the way to locked position?

I have new OEM rear diff fluid so I could always do that if it will fix it. Just a simple drain and fill I presume...no diagnostics needed?
 

·
Registered
Joined
·
410 Posts
It happens on tight left turns too, but very repeatable on right. It’s the diff plates locking and snapping to unlock to allow the differential motion of the inner and outer wheels. Tighter the circle the bigger the differential motion. It’s not an uncommon thing in RWD cars with high performance LSD. There is special fluid with friction modifiers to get rid of the noise. I think its called something like SAF XJ+ and kinda expensive. Technically all it does is make the plates slip more, which actually decreases traction in high performance driving. If you don’t track your car, drift, or power out of corners then you really don’t care about that.
 

·
Registered
Joined
·
410 Posts
You also could be low on fluid too or have a worn suspension link. A worn link could also be causing your excessive wear. I’d figure you’d kinda notice it other times when driving but that depends on how sensitive you actually are to how the car rides and drives.
 

·
Registered
Joined
·
368 Posts
I checked my car and agree on the negative camber in the rear. I set mine at -2, the front can only be changed if you remove the pin from the strut tower, mine with extra filing is -1.6. Tow is the biggest tire killer, you made it down to the wear bars so unless you want to give up some handling you will just have to live with it.

On the tire side I just removed Conti Extreme Sport contacts and was very happy with them. They talk a lot to let you know where the traction limit is. I now have Pilot super sports on and they don't make a sound, by my estimation they have less traction but not by much. 4S has been the gold standard for many years at the track. Cup 2's are just a pinch off of slicks and you pay for it. Fifty just put on R888 but I have not read a review yet? Unless you are looking for every second on the track the Conti's are the best bang for your buck and have a 40k warranty.
 

·
Registered
Joined
·
2,380 Posts
Discussion Starter #13
By they talk a lot....you’re saying the Contis are a loud tire? I don’t want noise. I have the pilot super sports now so i want something better or as good...if the Michelin p4s are the super sports made better then I’ll go that route. I don’t track. I just want quality summer performance tire (quiet and comfortable as I can get out of a 35 series sidewall)
 

·
Registered
Joined
·
368 Posts
They are not noisy, when I lean on them hard in a corner at the track they make noise before letting go. The Nitto's and Michelin's will not make noise they just let go. When I started taking my car to the track it helped me learn the limit by listening to the tires.
 

·
Registered
Joined
·
410 Posts
If camber is out, your toe will be out too. You have to adjust toe last. Stick with the factory specs if you are only street driving and want to preserve tire life.

If you are bored of being quarantined, you can check your rear toe quite easily with a tape measure, just measure along the same set of channels across the left and right side of the tires in the front of the tire and then the rear of the tire. The difference will tell you TOTAL toe. If you want to know the toe in from each side that’s a bit harder since you will need to measure to a body point that is known to be symmetric along the center axis. Rear toe that is asymmetric will cause a drift to the left or right, but you won’t know that since your front will help offset that and you’d have to know your front end was in perfect alignment too, which you won’t know without an alignment machine.

The picture you uploaded is classic excessive wear due to camber, excessive toe will cause a feathering pattern along with shoulder wear. You would see and feel that feathering when you get away from the shoulder. Any toe that severe in the rear with camber in spec will cause pretty serious drift.
 
1 - 16 of 16 Posts
Top