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tire wear

2K views 15 replies 10 participants last post by  Z3Papa 
#1 ·
my 96 z3 has completely worn out the inside 2 inches of both back tires, fronts are wearing normally, any thought on the cause, the Z has 130k on the odo, and is a second owner, am planning on a 4 wheel alignment next week when I put on my new Goodyear Eagle GT's, is there anything else I need to look for.:dunno:
 
#3 · (Edited)
... am planning on a 4 wheel alignment next week when I put on my new Goodyear Eagle GT's...
I don't think that camber in a Z3 is adjustable in the usual alignment, but it can be changed by adding camber bolts in front or other hardware in the rear, or made negative in the rear by broken springs. I would not buy the tires or get the alignment until the cause of the rear negative camber is corrected.
 
#5 ·
Many of us with lowered cars accept the negative camber and increased tire wear. Call it the cost of a performance car. If your car is on stock suspension and not been lowered, it is time for further inspection of springs, shocks, shock mounts, trailing arms, bushings etc. There is nothing an alignment can fix on these cars as there are no rear adjustments to be made (unless they have been modified with aftermarket adjustments) but it will give you a start on where to look for a potential problem.
 
#7 ·
Don't forget these cars normally wear out the rear tire faster than the fronts. And normally the inside of the the tires, especially the rear tires, wears faster than the outside.

How many miles are on these rear tires? Get a tire depth gauge ($10 or so at any auto parts store) and tell us the inner and outer tread depths. And, no, you can't accurately judge 1/32 inch increments by eye.
 
#8 ·
I don't buy the broken spring suggestion. Post up a side pic of your car. I'll bet it's lowered which would mean the weld in kits will be the best resolution to bring it back into spec.
 
#9 · (Edited)
I hate to admit it but when we bought our Z last spring, I thought the guy said he had just put tires on the back but now thinking back on it he MIGHT have said it would need tires soon, anyway I did not check the tread until the wife came home and told me it drove funny like a low tire, so I checked and sure enough a slow leak which prompted closed inspection and found bare steel on inside 2 inches of both back tires, we have put 10k on the car since purchase, I am sure the car is all stock, I am taking the wheels off today and taking them in for new eagle gt's, still gonna have 4 wheel alignment soonest, it is winter in N. Idaho and the car is put up for now, guess I will keep close eye on this first set of matching tires as the current front and rears are not the same. while I have it in the air I will give close inspection to the rear springs and replace if broken, at 130k miles I am sure there are thing I will need to catch up on, the original owner was a DR. and second owner a realtor for big realty company, I am confident no mods were done previously, these were all older upper class folks, thanks to all for the input, certainly gave me things to think about and look for.

UPDATE= got the wheels off today and everything looks normal, no broken springs or broken welds, after closer inspection of all 4 tires, I think its worn normally and things are in spec, all four tires were worn on the inside but the wear patterns are pretty even and the rears are more worn than the fronts, based on all the info I have found here I think I am in better shape than first thought, thanks to all for there input and wisdom as I have never owned a sports car before and am just learning
 
#11 ·
The reason I ask is that my Z3 had 18" wheels with 40-series tires and the tires kept wearing in the same way. I had to replace them every 6 months or so.

I switched from 40's to 45's and now, with more sidewall to flex, they last MUCH longer.

Sent from my SCH-R820 using BimmerApp mobile app
 
#12 ·
I'm not sure how you have 18" wheels and 45 aspect tires and still fit that within the wheel well without rubbing. That would push your diameter into the 26"+ range which is not good. It's not side wall flex which prevents this issue and if your tires are flexing enough to take pressure off the inside of a tire which would normally wear out with 35 or 40 aspect, it means you are seriously rolling over onto the sidewall which is even worse of an issue.
 
#13 ·
my z is running the stock tires 225-55-16's, I had a 4 wheel alignment done last week and it came back with no adjustments needed, it handles 1000 times better with matching tires on all 4 corners and I cant wait for springtime to arrive, feelin the itch for a road trip already, thanks everyone for all the responses :thumbup::rofl::bigpimp:
 
#15 ·
All the answers given here are good, but as said by others, you need to ascertain why/what is causing the excessive wear first.
From what I've read and gathered, this is a very common problem on the Z3 and can be from minor to horrendous.

I had a similar problem, in that my wear was mildly aggressive on the inside edge only of the rear left, and incredibly aggressive on a very small part of the inside edge of the rear right.

I have no broken springs and the car appears to be stock standard in height.
What I have read and gleaned from a lot of other more knowledgeable posts, is that as much as camber comes into this, it's in particular (in my case) a toe out problem.

Blacklane and others suggest the weld in plates and yes, they are a totally one fix solution, so you really can't go wrong. It's just that some like myself aren't quite ready to have these attached to the car... yet.

I really do suggest that in looking to why you have this problem, you also consider a couple of things.

1. the bushes, not only in the rear trailing arms, but in my case the rear beam bushes (the 2 big ones) were excessively worn, allowing the rear to squirm around and (I believe) cause unusual alignment and wear on my inside wheels. - I'm very happy to be corrected here by knowledge people.

2. as explained to me by at least 2 BMW savvy mechanics, that the root of the problem (if the bushes are good) is that something could be bent and the culprit might be the rear trailing arm itself. Only problem is, I've yet to come across a reasonably priced new trailing arm!

So, in my case, I fixed the rear beam bushes first and not only did it change the feel and driving of the car instantly, my excessive wear on the rear right, appears to have slowed down (very subjective of course, but I started with new tyres originally and in a very short time one of them had chewed out, but not now).

I still intend to change the rear trailing arm bushes, but in my case I decided to see if the Powerflex adjustable eccentric bushes would give me just enough control to at least slow down the excessive wear to a manageable level and then maybe I just change the tyres off the rims if I really want to extend.

That's my course of action at the moment and if that all goes pear shaped, then either new rear trailing arms, or the weld in plates, but at the moment, just fixing the rear beam bushes in the rear seems to have helped and that's a good start, but good luck with your odyssey and I'd certainly like to hear how you finally nail the problem.
 
#16 ·
If someone is going to drop the rear subframe to replace the rear trailing arm bushings and subframe bushings, please tell me you will go the extra step and have the camber/toe plates welded in since you are 95% of the way there when it comes to labor and the parts are ultra cheap. Afterwards, you will find some shops are reluctant to align the rear as it is not Z3 spec, but if you tell them to align the car as you would a 5 series, all will be good. It's correct, the alignment issues can be from a bent rear trailing arm and they cost a ton new. If that is your issue, your best bet is to hope to catch a deal from a car being parted out with hopefully only front end damage.
 
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