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      03-30-2012, 10:02 AM   #1
pingpong
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New rear tires causing DSC to go off?

I recently replaced my rear tires with a pair of Goodyear F1 Asymmetric 2. The fronts are still the previous version Goodyear F1 Asymmetrics. On sweeping freeway onramp and offramps, DSC kicks in very very early, causing the car to understeer pretty dramatically.

Now before anyone says "the tires need to be broken in", there tires have well over 500 miles AND I can't even break them loose on hard corners stomping on the accelerator, so I'm very confident that they have plenty of grip.

From what I've read, it seems like the rear tires are probably bigger than the fronts, resulting in the car thinking the rotational speed between the front and rears are off, causing the DSC to kick in. Assuming that's the case, is there any way to reset the sensor associated with the DSC? My front's still have about 40% tread, so I don't really want to replace them.
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      03-30-2012, 10:15 AM   #2
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Quote:
Originally Posted by pingpong View Post
I recently replaced my rear tires with a pair of Goodyear F1 Asymmetric 2. The fronts are still the previous version Goodyear F1 Asymmetrics. On sweeping freeway onramp and offramps, DSC kicks in very very early, causing the car to understeer pretty dramatically.

Now before anyone says "the tires need to be broken in", there tires have well over 500 miles AND I can't even break them loose on hard corners stomping on the accelerator, so I'm very confident that they have plenty of grip.

From what I've read, it seems like the rear tires are probably bigger than the fronts, resulting in the car thinking the rotational speed between the front and rears are off, causing the DSC to kick in. Assuming that's the case, is there any way to reset the sensor associated with the DSC? My front's still have about 40% tread, so I don't really want to replace them.
It may be as simple as having too much grip in the rear...turn off the DSC and see if it feels ok.
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      03-30-2012, 10:37 AM   #3
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Quote:
Originally Posted by prodigal_m View Post
It may be as simple as having too much grip in the rear...turn off the DSC and see if it feels ok.
+1

I'm not sure about the answer to your question about reprogramming DSC, but your conclusion about the difference in rotational speeds is accurate.
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      03-30-2012, 10:50 AM   #4
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DSC requires a circumferential difference of at least 5% to make a fuss. If you retained stock diameters then even fully worn front down to the cords vs brand new rears won't have more than 1% difference in overall circumference.

DSC's not the issue here. If there's a dramatic difference in age and use between the front and rear wheels, there can be a significant enough difference in grip for DSC to start complaining.
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      03-30-2012, 10:58 AM   #5
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Quote:
Originally Posted by The HACK View Post
DSC requires a circumferential difference of at least 5% to make a fuss. If you retained stock diameters then even fully worn front down to the cords vs brand new rears won't have more than 1% difference in overall circumference.

DSC's not the issue here. If there's a dramatic difference in age and use between the front and rear wheels, there can be a significant enough difference in grip for DSC to start complaining.
The thing is, if I turn off DSC and DTC the car handles just fine. With it on, it understeers pretty bad at speeds north of 50 on gentle curves (scared the crap out of me the first time that happened). South of 50 I can toss it around even with the DSC on and it won't kick in.
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      03-30-2012, 11:01 AM   #6
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Buy new front tires...problem solved.
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      03-30-2012, 11:04 AM   #7
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Quote:
Originally Posted by prodigal_m View Post
Buy new front tires...problem solved.
I would but I still have a ton of tread left in the front. Odds are once the new rears wear out the fronts will need to go too, but to replace all 4 at the same time is pretty pricey.
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      03-30-2012, 11:33 AM   #8
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Check your tire pressures too
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      03-30-2012, 11:42 AM   #9
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Quote:
Originally Posted by Roffle Waffle View Post
Check your tire pressures too
Checked those, 33/38 which is what the manual says.
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      03-30-2012, 01:08 PM   #10
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38 rear? Whaaaaaaaaat? Check your door jamb
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      03-30-2012, 01:48 PM   #11
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Quote:
Originally Posted by Roffle Waffle View Post
38 rear? Whaaaaaaaaat? Check your door jamb
That sounds about right. For my 07 Si with 225/40f and 255/35r the door jamb sticker shows 33f and 39r. From other posts, it seems that BMW dropped the pressure to 38 for the rears on later cars?
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      03-30-2012, 01:54 PM   #12
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I thought the door said 30/30 for the M's? Do not know about the others...
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      03-30-2012, 02:07 PM   #13
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I run 35psi all round. Perfect.
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      03-30-2012, 03:13 PM   #14
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Quote:
Originally Posted by Incompatible View Post
That sounds about right. For my 07 Si with 225/40f and 255/35r the door jamb sticker shows 33f and 39r. From other posts, it seems that BMW dropped the pressure to 38 for the rears on later cars?
My 07 si with the sports package (225/40, 255/35) says 33/38 on the door jamb. Mines a roadster though, so many it's 1 less than the coupe?
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      03-30-2012, 04:08 PM   #15
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Quote:
Originally Posted by davesz4mc View Post
I thought the door said 30/30 for the M's? Do not know about the others...
exactly what I run, thats why I was so surprised
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      03-30-2012, 04:09 PM   #16
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Quote:
Originally Posted by Beedub View Post
I run 35psi all round. Perfect.
drop the rears to 30psi for better traction broski
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      03-30-2012, 04:46 PM   #17
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The tire pressures in the door are the safe UNDERSTEER pressures.
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      03-30-2012, 04:59 PM   #18
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Quote:
Originally Posted by Roffle Waffle View Post
drop the rears to 30psi for better traction broski
30psi is way to low for me...... i do more track work remember, ideal hot temps are 40psi, im running the stock CSL rims with stock csl sizes, they were bmw recommended 35psi all round and this works very well for me... i tried it lower and i dont like the soft feel to the car.....
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      03-30-2012, 05:49 PM   #19
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Guys,

OP has a 3.0, not an M I believe. Recommended pressures are not the same across M and non-M models.
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      03-30-2012, 07:28 PM   #20
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OP - What tire sizes do you have on the car right now?
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      03-30-2012, 09:31 PM   #21
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Quote:
Originally Posted by The HACK View Post
DSC's not the issue here. If there's a dramatic difference in age and use between the front and rear wheels, there can be a significant enough difference in grip for DSC to start complaining.
pingpong,
Here's how to determine the production date - http://www.tirerack.com/tires/tirete....jsp?techid=11.

While you're looking, check for dry rot, which looks like fine cracks in your tire. When it occurs, I usually see it around the base of the tread blocks.
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      04-02-2012, 01:33 PM   #22
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Quote:
Originally Posted by pokeybritches View Post
OP - What tire sizes do you have on the car right now?
OEM sizes: 225/40 fronts and 255/35 rears.
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