07-27-2016, 02:00 PM | #1 |
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M235i tire pressure
Ive been wondering why bmw recommeds 5 psi more in thr back. I thougt that its just for safety. So
Ive been driving with even tire pressure and its resulting in more body roll and no feel right. I just put 3 psi more in the back and feels alot better. 34 37 cold. I dont know its becuas i got all season rfy tires or not. This car is very sensitive to the pressure |
07-27-2016, 10:08 PM | #4 | |
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http://www.tirerack.com/tires/tirete....jsp?techid=58 |
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07-28-2016, 07:57 PM | #7 |
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like which?
tire grip is like a pyramid .... there is an optimal pressure where you will get the most grip.... to either side you will start loosing grip.... the thing is that usually the optimal pressure is fairly high say 38-40 psi.... so in most cases the you are on the left of the peak which means that if you lower the pressure you will be losing grip... now if you are at 40 psi and you push it to 45 psi now you are going the other way and you will also lose grip cause you will be reducing the contact patch... |
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07-28-2016, 08:31 PM | #8 |
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Can we say we're both right and wrong? There is no hard and fast answer to 'do x to get x' when it comes to tyre pressures as it will depend heavily on the car, type of tyre, where your pressures currently are etc...
Using your pyramid, if you're on the underinflated side of it on your fronts (i.e. under the peak grip), increasing them increases their grip relative to the rear i.e. cancelling out understeer/possibly to the point of inducing oversteer. Other way still stands. Assume your fronts are at peak grip, overinflating your rears to reduce grip and suddenly you have a oversteering car. As for those sites... https://www.facebook.com/notes/ultra...0134442380550/ http://www.trackdayguru.com/tyre-management.html |
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07-28-2016, 08:56 PM | #9 | |
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Also increasing tire pressure, will increase your spring rate which will lead to understeer... so there are more factors than just grip but usually spring rate doesn't make such difference as the grip from the tire even the 2nd site you posted shows... Symptom Pressure Adjustment Understeer Increase Front or reduce Rear 2 psi * Oversteer Increase Rear or reduce Front 2 psi * as for the facebook guy... I think he is just wrong |
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Tpeterson156.50 |
07-29-2016, 10:17 AM | #10 | |
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http://store.uucmotorwerks.com/artic...ybar_setup.htm |
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07-29-2016, 03:32 PM | #13 | |
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I run 235 and 265 staggered. 38F and 40R cold
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FBO M235i r
F80 M3 |
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07-29-2016, 03:48 PM | #14 | ||
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PSS are fairly soft sidewalls so they will roll over if not inflated well |
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koston37.00 |
07-29-2016, 07:51 PM | #15 |
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07-29-2016, 07:54 PM | #16 | |
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So I do have more pressure in the front than stock |
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07-29-2016, 08:20 PM | #17 |
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07-29-2016, 08:47 PM | #18 | |
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When it says more it means more pressure than before, not necessarily more pressure than the rear. But for the track I would run 33F-31R if you have a decent track tire |
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