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Rear tire wear 09 35i

Discussion in 'E85 Z4 (2002-2008)' started by ericprouty, Feb 14, 2011.

    ericprouty guest

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    I've just been informed that I need both rear tires replaced on my 09 Z4 35i with only 12,500 mi (inside of each worn down). I was told it's either because of improper inflation (not an issue with me) or a misalignment. Anyone else with this issue? I've read lots of bad things about these run-flats. Can they be replaced with non-RFTs?
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    Zeichen311

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    Yes they can but you'll probably chew through conventional tires just as quickly. Run-flats aren't at fault here.

    The natural rear suspension geometry of most BMWs puts more load on the inner edge of the tires. This is by design--it's called negative camber and it's a large part of why these cars corner so well. The down side is that drivers who tend to have a heavy foot only in a straight line (especially from standing starts) wear out the inboard edges prematurely. It may seem counterintuitive but the tires actually last longer, and wear more evenly, when the cars are driven harder in the corners. (Up to a point, of course. ;))

    Correct inflation and alignment will minimize the problem but if most of your driving consists of sprints between the stoplights, it won't go away.
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    granthr

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    +1 What he said! :D

    ericprouty guest

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    Thanks

    Thanks for the reply. I very rarely accelerate quickly in a straight line, and my aggressive driving is almost always in cornering (even then my overall driving is not very aggressive). Is 12,500 miles to be expected for rear tire life? That just seems ridiculous and I'm not happy about plunking down $1000 at the dealer for two rear tires 16 mo after buying the car. You said I'll chew through non-RFTs just as fast as RFTs, but at least they're cheaper.
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    Pyewacket1

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    The RFT issue has been debated to death, IMO.

    Just "Google" run flat tires and you will get links to far more information and opinions that you would ever wish to read or know.

    Personally, I wouldn't buy tires from the dealer. Go straight to a reputable tire store locally or Tirerack.com... You will save $$$, regardless what style tire you select.

    My wife got 50K miles out of a set of RFT's on her 2005 MINI, so I know its possible, but her experience certainly doesn't appear to be the "norm".

    If you do choose a non RFT option, you must decide what to do about flats. Again, the opinions on even that run from soup to nuts.

    Good luck!
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    Zeichen311

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    I mentioned quick acceleration because that tends to exaggerate the problem. It's not a requirement, though: Wide, high-performance tires, an aggressive negative camber setup and a relatively gentle cornering style add up to accelerated inner-edge tread wear. This isn't unique to BMWs--many high-performance cars are set up this way.

    As for the mileage, the answer is of course "it depends." Have a four-wheel alignment performed, ask them (up front) to provide a diagnostic printout with the before and after measurements at all four wheels, and look for any significant difference in the rear wheel camber angles. If there is none, yes, 12,500 miles is all you can expect for your driving style on that tire brand and model.

    I second the suggestion to check out local tire shops and/or Tire Rack, if your dealer wants over a grand. You can save hundreds off that figure, even for run-flats.

    You can also try keeping your rear tires routinely over-inflated by a few PSI. That will take a little of the load off the edges of the tread, which given the wear pattern you've experienced might lead to slightly improved tire life overall. Don't expect miracles, though.
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    eam3

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    I got about 12,500 miles out of the rears on my E46 and when I went to the dealer to ask if this was normal, I noticed there were little signs at every advisor's desks explaining that 12,500 is average for the rears on new BMWs. Because my car was a CPO purchase, it came with brand new RFTs (not what it had from the factory when new) and the ride was horrible. I decided to buy 4 brand new regular tires (even though the fronts were less than 50% worn) and my car is simply a joy to drive now. Gone is the harsh ride, tire noise and average handling. Granted, that may be due to the fact that it was never engineered to ride on RFTs in the first place but the difference was huge. I cannot believe the dealer put those tires on the car to certify it, they were horrible.

    Our E60 535i (w/sport package) came with RFTs and the ride was nothing to brag about either, it was rather stiff, but tire wear was not as bad, we got 39K miles out of the fronts and about 30K out of the rears.
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    BMWCCA1

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    That makes no sense. The E46 wheels weren't designed for Run-Flat tires. The only CPO requirement is that a car have the same specification tire it came with from the factory with a specific remaining tread depth. This would never have been interpreted as Run-Flats on an E39, in fact it would require the opposite. What kind of dealership are you dealing with and did you ask them why it had Run-Flats? I'm not even sure it's safe to put Run-Flats on a non-Run-Flat wheel, though the converse is a valid application (non-run-flats on a run-flat wheel).

    Sport-Package E60s were the only E60s that got Run-Flats, even though you still got a spare.
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    eam3

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    Yeah, I know but I think the dealer just mounted whatever they had in stock before putting the car in the showroom. I had no experience with RFTs so I didn't think anything of it when I saw them mounted on the E46. It was only after extended driving that I began to hate the ride, handling (or lack thereof) and noise in my car, I seriously didn't understand what the big deal was about the ZHP package until I swapped out the tires. 10K of regular tire driving later I understand, I love this car.

    For what it's worth, it was Vista BMW in Coconut Creek, FL. I think their general attitude is "If the car is more than a year old, it's kind of an inconvenience for us - we only care about the current product line". I could be wrong but that's my impression.

    I'm really glad that our E60 had a spare because we had one of those cases where no amount of RFT technology would have gotten us to our destination. It is for that reason that my wife won't even look at a new BMW. No spare = no deal in her book.
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    MGarrison

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    Unless your rear tires are asymmetric, if the wear for both is the same, you might be able to extend usable life by flipping them on the rims. If the rims for some reason are directional (unlikely, I suspect), the tires would have to be dismounted from one rim, flipped, and remounted on the other rim. A bit of a nuisance I know, but a possibility if you don't find any other issues. You'll have to gauge whether the expense and time of having them flipped, possibly several times, can extend the life enough to be a savings over just allowing them to wear out.

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