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View Full Version : what's normal tire wear?



dsames
06-22-2005, 10:32 AM
This being my first BMW, I'm wondering what "normal" tire wear looks like for regular street use. I have Kumho712's on the car for about 9 months now (I'll have to figure out how many miles that is... <20K, anyway), and it looks like the inside edges of the rears are wearing quite a bit faster than anything else. The fronts aren't quite as worn out, but there is a similar pattern. Outside edges are less worn than inside, and there is definitely wear in the middle. Tire pressures are whatever is recommended on the info panel (don't recall what I set them to at the moment).

Any thoughts?

Thanks,

Dave

1996 328ti
06-22-2005, 12:13 PM
Is your car lowered and what model car is it?

dsames
06-23-2005, 08:34 AM
No - it's not lowered, it's an '99 328i. I did put a '98 M3 staggered wheel set on, and the relevant tire sizes, however.

Thanks

bren
06-23-2005, 11:38 AM
I don't think it's entirely abnormal for the insides to wear a bit faster than the outsides (so long as it's even on both sides of the car.)

Of course if the alignment hasn't been checked in a while it certainly wouldn't hurt.

Doby
06-23-2005, 12:21 PM
How many miles are on your car? The springs do get old and sag. With that sagging, the car ends up with more negative camber and will then wear the inside of the tires faster then the outside.

I'd suggest the when you get new tires, have it aligned again.

AG
06-23-2005, 12:49 PM
Worn shocks and bushings could do it too, no?

Doby
06-23-2005, 01:18 PM
If the springs are sagging, then yes the shocks are done too.

There is a camber problem in the rear causing the inner tire wear, but since he has ~20k miles on the tires, I wouldn't think the RTAB's are that bad. Bad RTAB's can cause the rear tires to wear down in ~5k miles. If they were bad, I would think that the tires would have been toast before the 5K.

dsames
06-23-2005, 02:50 PM
Okay - some more info - ~75K on the car. I haven't had an alignment done in the time I've had it (since ~38K miles). I don't recall there being an alignment in the service records, but I should check. The wear appears pretty even on both rear tires, and as I mentioned, some on the fronts, but not as much.
Suppose I should have the alignment checked when I get new tires next time around.

On a side note, are there suspension components that should be replaced at some regular interval? I've heard some claims that control arm bushings go around ~60K, but I haven't noticed any significant changes.

Thanks!

Dave

Doby
06-23-2005, 03:02 PM
You stock shocks/struts are probably toast, along with your LCA bushings, and RTA bushings and your rear shock mounts.

maditalian
06-24-2005, 12:48 AM
You stock shocks/struts are probably toast, along with your LCA bushings, and RTA bushings and your rear shock mounts.

how often sould one change the shocks/struts and springs :icon_conf
mine have 31k and my car is a 01 m3, a guy i know whats to sell me his zcp package m3 suspension w/ like 1k miles on it (he got H&R's) for like 350 bucks and i have been thinking about it
watcha guys think i should do ?

ChosenGSR
06-24-2005, 05:33 AM
how often sould one change the shocks/struts and springs :icon_conf
mine have 31k and my car is a 01 m3, a guy i know whats to sell me his zcp package m3 suspension w/ like 1k miles on it (he got H&R's) for like 350 bucks and i have been thinking about it
watcha guys think i should do ?
I think thats way early, also I would go aftermarket if I was to to upgrade.

OwnedbyDuncan
06-24-2005, 08:11 AM
Shocks and springs. Shocks typically start to go at around 40k miles under normal conditions. Springs under normal conditions dont really need to be changed. If you track the car or do Autox around 75k.

If you are going to replace the shocks and are considering new springs. I would do it all at once. Same labor costs or time if you are doing it. You can replace the bushings too. And only pay one time for alignment. I prefer stiff springs and small sway bars. I use the sway bars to tune the car. Big bars have a tendency to rip the mounts out. Also find a quality shop to do the work and the alignment. Not Manny, Mo and whoever. Shocks bars, springs and camber plates need to be installed correctly with no preload etc. Alignment done with a full tank and if you are lucky with you in the car.

dsames
06-24-2005, 08:30 AM
Unfortunately, I'll have to show ignorance here, but, what are LCA bushings, and RTA bushings?

So, now I have to ask the obvious question - what are good replacements for these things? Might as well upgrade while I'm in the process, right?

1996 328ti
06-24-2005, 12:57 PM
It might be time to add a glossary. ;)

LCA Lower Control Arm
RTA Rear Trailing Arm
RTAB Rear Trailing Arm Bushing

OwnedbyDuncan
06-24-2005, 05:41 PM
Forgot to mention make sure the springs you buy work. Many years ago when I was looking for springs some from major suppliers just did not work. Some were softer than stock, some bottomed out and others suffered from coil bind. These were springs from a big time BMW/Porsche after market supplier located in Alexandria, another firm whose initials are ST and a big name spring manufacture whose name begins with E( did buy their comp springs). A major West Coast BMW tuner would not give me their spring rates. Hell for what they wanted for their suspension packages they should have tested each spring individually and put the spring rates on a nice polished plaque. If you autox or do schools do some research and ask questions. There are very few shops out there who know about springs, shocks, bars and camber plates etc but they will be than happy to take your money and install them. Having coil bind down the chute at Summit Point is not the fast way and may be a real scary way!

Doby
06-24-2005, 09:38 PM
All of the spring rates from all of the major brand names (H&R, Eibach, etc) are fine... it's the lack of length that's a problem. :-p For any car that's going to be track a lot something along the lines of coilovers would be a better idea, but for a street car on street tires used for some tracking, a simple off the shelf Eibach or H&R would be fine.

And to coilbind an off the shelf spring means that the car didn't have the correct bump stops on the shocks, or the shocks were too short.

But to get back to the original question. I would suggest all new shocks and RTAB's. Maybe look into new front control arms and LCA bushing in the future. While doing shocks, if you ever plan on lowering the car, then new springs would be a good idea. A lot of people think that the springs on the cars never go bad, but they do. If you notice how low some cars sit, that's because of the springs being old. 3200lbs sitting on springs will wear them out.

I helped align a car with the new Bilstein BTS kit on it and I was very impressed. I think you can find the kit online for under $700 and it's a matched set of shocks and springs. The drop was perfect and the car rode great for a street car.

OwnedbyDuncan
06-27-2005, 08:28 AM
Wrong on an E30 coil bind was a spring problem and not a shock or bump stop problem. And occured in several after market suppliers springs. Just buying an off the shelf spring or a spring and shock kit does not guarantee that the combo will work. Many after market springs and spring/shock kits are sold simply to lower the car and close that gap between the tire and the fender. Eibachs Prokits are a good example of this.
I will say again do you research. Many of these springs even in kits sold by reputable companies have spring rates the same or softer than stock. Make sure you have the right shock for your application. IE for an E30 Bilstein SPorts for shorter and stiffer springs.

Doby
06-27-2005, 08:44 AM
Ah, ok, so you're talking E30's while the thread was about E36's. Sorry for my confusion since the orginal poster was asking about his E36.

The Eibachs and H&R springs for E36's have higher rates then the stock E36 springs. To coildbind an E36 means exactly what I stated above.

dsames
06-27-2005, 09:17 AM
Just to confuse matters a bit more, perhaps, I was talking about an E46 - note the '99 328i designation. Should have been more clear on my part. As far as I can tell (from the bilstein site, anyway) they don't provide a BTS for the E46.

Thanks,

Dave

Doby
06-27-2005, 09:19 AM
Awesome, a 3rd model year. The E46 rear suspension is similar to the E36.

OwnedbyDuncan
06-27-2005, 10:15 AM
For an E46 I would go with E46 M3 springs, Bilstein shocks(HD) and sway bars. For the sway bars go with adjustability over size(stay small rather than larger on the bars). While the suspension is a part replace the shock bushings and control arm busings etc. Not sure with an E46 if Bilstein Sport and HD are valved the same like on some other BMW models. You should be able to get a set of M3 low mileage take off springs cheap. Do all the work at once saves on labor and alignments. You may want have the front lower control arms replaced at the same time. You could go with BMW M3 sway bars. Make sure whoever is installing all this knows what they are doing. Know several individuals who had similar work done on a variety of cars where the mechanic preloaded the suspension. Was not fun chasing this.

SharkD
06-28-2005, 04:39 PM
You could always try flipping the tires on the rim and then swapping RR x LR, FR x FL...

If you want to be religious about it, do it every 6,000 miles (or 3k if you track it on street tires).

BTW, don't feel too bad, my e24 has almost chewed to the wear bars on the insides of my rear AVS ES100's in less than 9,000 miles -- but that's mainly due to A) weight, b) high torque + an LSD, and c) the (intentional) negative camber I've dialed-in.

AlfaEric
06-28-2005, 05:01 PM
BTW, don't feel too bad, my e24 has almost chewed to the wear bars on the insides of my rear AVS ES100's in less than 9,000 miles -- but that's mainly due to A) weight, b) high torque + an LSD, and c) the (intentional) negative camber I've dialed-in.
Be happy. I've got plenty of negative camber yet I'm wearing out the outside of my ES100's. The only solutions that were offered to me were to go to -4 (for street!?!?) or stop driving like an idiot. :icon_doh:

---Eric

dsames
08-12-2005, 08:50 AM
I was curious about the RTAB - could that also be referred to as the Rear Trailing Arm Toe Bushing? Or, is it something else? I'll have to consult my manual when I get home, but was curious about the terminology.

Thanks,

Dave