rear tire inner wear - pix inside

[TheDeep]

so i swap my tires every winter and spring and i've never noticed any problems with uneven wear on any tire, except this time when I took off the summer tires yesterday. Both rear tires are quite worn on the extreme inside edges, both equally.

Thing is....I've done nothing that may explain this. No suspension work, no hitting anything...the only thing I did is change brake pads 3-4 months ago and I can't fathom that causing the rear alignment to go out of whack.

A local, reputable shop says that very little adjustment in the rear tires is possible, and over the phone they can't offer any explanation why this would have occurred. Any suggestions?

TIA

http://img.photobucket.com/albums/v128/mpowerdeep/DSC_0004.jpg

http://img.photobucket.com/albums/v128/mpowerdeep/DSC_0003.jpg

[pauliodotnet]

that is camber for you. rotate your tires more often.

[giterdone]

how many miles are on the tires? but the inner wear is negative camber. Do you know how much you have? it might be a bit extreme.

[first time]

I was searching a few days ago on the same topic. Mine are doing the same thing. I have to believe we are looking at some very specific suspension components to address. My car has 28k. Anyone...

[busterhax]

just too much negative camber. i have the same problem, except with front tires too. just have each side swapped every x miles. like when uneven wear starts to become visible, mark how many miles that was. switch drivers side tires with passenger side tires. then repeat when the x number of miles occurs again

[4ZPN]

A worn rear trailing arm bushing (RTAB) can cause accelerated wear on the rear tires.

[malter]

it is normal. stock m3s have about -1.5 degrees of neg camber in rear. add to that probably worn RTABs and result is in your picture. camber is not adjustable in front or rear.

[EURO M3 CSL]

camber is not adjustable in front or rear.

uh.. yea it is...

fronts: u can rotate ur strut hat to gain or reduce camber AND caster. if not.. add 2 washers to the 2 bottom bolts of the shocks to gain instant camber setting

rears: lower control arm adjusts camber

[TheDeep]

Bentley manual says "Front and rear caster and camber are both fixed by the design of the car. Any deviations are usually the result of worn or damaged suspension or body parts."

How do I know if my RTABs are bad? I read somewhere that one test is: Drive to 40mph, then brake hard without touching the steering wheel. If the car pulls to one side, RTABs are bad. Likewise, drive to 40mph in 2nd/3rd gear, then floor it. If the car pulls to one side, RTABs are probably bad. Does this sound about right?

[RRSperry]

Ok, I chime in here. It probably isn't camber, it's toe. Take it to a shop that KNOWs how to align a M3

[TheDeep]

How much should I expect a shop to charge me to replace both RTABs?

[ohlins8990]

I know on my Saab, I have camber bolts. Its basically an elliptical bolt that allows about a degree worth of camber adjustment. It goes right where the strut meets the hub. I'm sure BMW has something similar.

[MoeMuny]

+1 on finding a shop that know what they are doing....

a bent rear lower control arm can cause this as well

[busterhax]

RRT charged me 2.5 hours for RTABs

[TheDeep]

Took it to the shop. Guy said there's nothing wrong with my car. He looked at the tire wear on the inner edge and said that's normal pattern after 20k miles. I didn't tell him I've done 40k+ miles on these tires. He suggested that if anything, ♠I get alignment checked since I haven't done that since 2003...so that's what I'm getting done....will get the car back on Monday..and will post the results here.

[Tim95M3]

looks normal to me.
Rear camber is adjusted where the lower control arm meets the trailing arm

[polishracing95]

camber.... go get a alignment

[QuickSilver M3]

you need to rotate your tires more... that's normal wear and tare. is your car lowered at all?

[TheDeep]

looks normal to me.
Rear camber is adjusted where the lower control arm meets the trailing arm

yeah the shop guy took the time to explain it to me but also said there's little adjustment that can be done in the rear, not a whole lot.

[TheDeep]

you need to rotate your tires more... that's normal wear and tare. is your car lowered at all?

car's stock. Nothing to do with tire rotation, since I rotate them every 7-8 miles but have never noticed any uneven wear. This is the first time I've seen this, and it's only in the rears. Both rears are worn on the inside edge, just the one innermost section of tread. I know the stuff about negative camber on the rears, but then, I should have noticed some gradual wear over the years. I bought these tires in 2003 and next year I'm going to get a new set. Saving these tires is not the point; I'm just trying to ascertain if anything is broken in the suspension that will cause new tires to get f-ed up too. So yeah, an alignment seems to be the first thing to do.

sorry for the long-winded post. i'm not high or anything.
:)

[5150taxi]

You guys do know, that there is rear camber AND TOE!!! Put it on a good alignment rack, and there ya go. I can almost guarantee the toe is out of spec!

[houstonm3]

i had the exact same issue, my rear tires would only last 3-4k miles, i had to replace rear tires more often than oil, its the RTAB's definatly get that checked.....

[Eric98Sedan]

You guys do know, that there is rear camber AND TOE!!! Put it on a good alignment rack, and there ya go. I can almost guarantee the toe is out of spec!

BINGO!!!!

Some of you guys got some readin' to do.

It's not the camber, it's the toe OR toe change caused by worn RTABs. I run -2.5 front camber and my tires wear nearly perfect because I run zero front toe.

Btw.... those tires look great for 40k!!!

[svart]

Agree on the toe.

[TheDeep]

NO. Just got a call from the shop. They did the alignment. The front was perfect. The rear camber was off by VERY little - nothing that would cause any problem. Toe measurements were as per spec.

I'm guessing that since these tires are 4 yrs old...and have seen at least 40k miles...over time, the rubber compound got hard and the inner wear became accelerated because the rubber couldn't 'yield' to the negative camber. Besides, the inner wear became more apparent because there's not much tread left on the tire now. Whatever, I'm just going to replace the tires in Spring and forget about it. All suspension bushings check out ok.

[AxisPower]

Toe and camber affect one another when doing an alignment. I was fortunate enough to have my alignment done in front of me and I could see how the adjusting of one would affect the other. A good way to think about why this is the case is if you think of the trailing arm as a fulcrum...as you retract the lower control arm, toe begins to point out and vice versa. Its a tricky game they play when getting these cars aligned right. Camber and toe are obviously the culprits, but these aren't tangeable. Whats the cause of your camber and toe misaligments is the real question. Could be bushings, bent control arms, trailing arms, etc...check everything...oh and 40k on most summer rated tires is considered worn and should to be replaced.

[Motorsport333]

negative camber.

[TheDeep]

Toe and camber affect one another when doing an alignment. I was fortunate enough to have my alignment done in front of me and I could see how the adjusting of one would affect the other. A good way to think about why this is the case is if you think of the trailing arm as a fulcrum...as you retract the lower control arm, toe begins to point out and vice versa. Its a tricky game they play when getting these cars aligned right. Camber and toe are obviously the culprits, but these aren't tangeable. Whats the cause of your camber and toe misaligments is the real question. Could be bushings, bent control arms, trailing arms, etc...check everything...oh and 40k on most summer rated tires is considered worn and should to be replaced.

the shop checked everything. there's nothing wrong with the car. yes i know the tires are shot. I was going to replace them next season, whether I saw this wear on the inner edge or not.

[XelderX]

Camber doesn't wear tires unevenly by itself. The combination of camber with toe will cause accelerated uneven wear.

[XelderX]

Also...to the OP...

Just have the tires flipped on the rim. Then you can get a little more life out of them.

[zmmnm3]

HI, 97 M3 here with the same wear pattern on the rears. I replaced the Rtabs and when I got it back from the show the camber was set to 0-.5 rather than the 1.75 called for in the spec. I know this affects handling but I am letting it ride for now to see if I get better tire wear. Don't know on the handling since i have not been to a school yet to see how it works. FYI I have 8.5 X 17 with 235/40/17 all around.

[dcroghan]

I wouldn't worry about it. 40k and your tires look like that? I would kill for that.

[blueballs534]

LOL... that is some funny sh*t. I wish. Mine last about 4k and without aggressive commute driving. In the near I sill start a new thread with the story and pics.

[Mekihead]

For starters, I'd give my left nut to have my tire last half of what you get out of them.

Secondly, I'm willing to bet you're driving on the stock Rear trailing arm bushings(RTABs). When these wear out, they tend to do this as well as encourage the rear to step out under load. You're driving on a 14 year old suspension. Just replace all the rubber suspension componants. It'll be night and day difference

[geoffm3]

40k miles is a lot!

I had some nasty wear on the inside of the back tires. New RTABs and alignment seems to have cured that.

[bhallid]

I had tires with less than 12k that were bald on the inside because of worn RTABS - a bad rtab will kill a tire!

[LagunaSecaBlue]

I was searching a few days ago on the same topic. Mine are doing the same thing. I have to believe we are looking at some very specific suspension components to address. My car has 28k. Anyone...


pics of your 28k car

[wingnut1961]

Took it to the shop. Guy said there's nothing wrong with my car. He looked at the tire wear on the inner edge and said that's normal pattern after 20k miles. I didn't tell him I've done 40k+ miles on these tires. He suggested that if anything, ♠I get alignment checked since I haven't done that since 2003...so that's what I'm getting done....will get the car back on Monday..and will post the results here.

40K+ on those tires! I say congratulations and go celebrate by buying some new ones.
:redspot