Rear wheel balance (toe in angle)

[mike540]

About a month ago one of my rear tires failed on my 95 540. When I removed the wheel I noticed my tires were coned < on the inside. I just brought my car to have a wheel balance and was told by the mechanic that there are no adjustments to balance out the rear wheels, but he could tell that the rear whell needed a balance.

My car is a 95 540 with 165,000 miles riding on 18in BBS wheels. I have had this car for the last 65,000 miles. This is the 3rd set of tires, and I never had this problem before. Is there a known problem that goes wrong on E34's, is my suspension shot? should I just bring it to a BMW shop and get raped on the price to get it fixed?

[Rigmaster]

Hmm. Sounds like we need to get your terminology straight. You mentioned "balance" a couple of times, with a couple of different meanings (I think).

Balancing a wheel/tire is just to make it ride smooth, and (hopefully) allow the tire to wear evenly. It cannot cure a bent wheel or damaged or misaligned suspension.

Your mechanic is correct that there is no adjustment that can be made for the rear wheel ALIGNMENT. Alignment is done by making sure the wheels/tires are not leaning in too much (camber) or pointing in or out too much (toe in or out) using adjustments in the suspension pieces (if available). Most BMW's have no provision for alignment on the rear, and only toe adjustment on the front- without replacing pieces (offset bushings or upper strut bearings, etc).

If you can clarify what exactly the mechanic told you- we can better try to help you.

EDIT- after re-reading the subject line- it looks like the TOE is out of whack in the rear. The only adjustment can be done by installing adjustable trailing arm bushings and having it set by an alignment shop.


Bret

[jjw]

Right, there is no adjustment provided for the rear. I have the same type of tire wear on mine. Although mine is lowered and runs on 18" tires. One way is to check tire wear more oftern and have the tire flipped inside out once a while, it may cost some $ for tire shop to do it, but still better than buy new tires when half of the tire still good.

[Jay 535i]

Right, there is no adjustment provided for the rear. I have the same type of tire wear on mine. Although mine is lowered and runs on 18" tires. One way is to check tire wear more oftern and have the tire flipped inside out once a while, it may cost some $ for tire shop to do it, but still better than buy new tires when half of the tire still good.

Huh? If the tire's non-directional, why not just rotate it rather than flip it on the rim?

If it is directional, then flipping it won't help cuz you'll have to mount it on the other side of the car and you'll have the same problem -- just in mirror image.

[jjw]

For me, rotate them doesn't help, since they all wear on the inside. As for none directional, you can just flip on hte same wheel and on the same side. But for directional, you have to flip and change to other side, so inside of left tire will become the outside of right tire. Only tire won't work is Asimetrico tires.

[mikell]

Have you checked your "dogbones"?

[Jay 535i]

But for directional, you have to flip and change to other side, so inside of left tire will become the outside of right tire.

No. If you flip and rotate, the outside of the right tire will become the outside of the left tire. So that won't solve your uneven wear problem if it's due to excessive camber.

[jjw]

Trust me, it work. I have been doing this for the last two sets of my tires. Just try to see, maybe draw a picture will help.
If you just flip the tires, will it be inside become outside? But for the directional tires, you can't put the same tire at the same spot, because rotational directions, backward. So you put it on the otherside of the car, and it will be the right direction rotation and inside become outside.

[mike540]

Yes the toe in angle is off. The rear wheels are angled in. I am getting more wear on the insides of the tires. I have been through 2 set of tires and never realised the wear before.

I thought the M5 (or 540msport) ran 18 in wheels. So I figured there has to be somthing to correct my problem. the wear would be like this > <

[Kalevera]

I don't know if I'm understanding this correctly, but..I mean, to be frank, with no rotation and (IMHO, too large) 18" wheels, 20k+ miles for one set of tires is very good.

The suspension has negative camber in it from the factory, and throwing larger wheels and low pro tires on it exacerbates things. Fronts wear on the outside, rears wear on the inside.

The car may have worn trailing arm bushings (where they meet the subframe), but an alignment would more than likely show one side with significantly more toe than the other. You could have two bent trailing arms...always a possibility if the car has been in an accident or has gone over stumps/hit curbs/the like. The car could have an extremely dead set of rear shocks, two broken rear springs, or blown out shock mounts that would cause the rear end to drop a few inches and put more weight on the inner edges of the wheels; but you'd know about it when driving the car. All of these situations are unlikely, though...I think it's just another negative aspect of running 18s.

EDIT: as previously mentioned, checking the dogbones is a good idea.

best, whit