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X5 E70 (2007 - 2013)
E70 BMW X5 produced between 2007 and 2013. Discuss the E70 X5 with other BMW owners here.

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  #1  
Old 07-07-2012, 04:43 PM
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ductman ductman is offline
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Tire PSI ?

I am currently following the BMW recommended 32/36 PSI, I did rotate my tires and have noticed the rears have slightly more tread wear in the centers, sign of over inflation , Is anyone running the same pressures front and rear and why would I not run 32/32 front and rear if I am not carrying any extra load ? I have noticed all German cars run different front to rear inflation pressures while the others do not .
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  #2  
Old 07-07-2012, 06:46 PM
alexmish alexmish is offline
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I am following recommendations, too, and seeing similar - more wear in the center... Mind that I do wheel alignments every 5k miles... Do you run 18, 19 or 20" tires?
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  #3  
Old 07-07-2012, 11:32 PM
ard ard is offline
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I do not follow their recommendations as their recommendations are derived from a FULLY LOADED CAR.

Given that 95% of the time there is a 110lbs driver in the car, I run 36 front, 34 rear. I hate chewing up the outer edge of the front tires, so I typically run a bit more pressure up front- and this makes sense as most of the weight is up front,
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  #4  
Old 07-08-2012, 05:43 AM
davidc1 davidc1 is offline
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Quote:
Originally Posted by ard View Post
I do not follow their recommendations as their recommendations are derived from a FULLY LOADED CAR.

Given that 95% of the time there is a 110lbs driver in the car, I run 36 front, 34 rear. I hate chewing up the outer edge of the front tires, so I typically run a bit more pressure up front- and this makes sense as most of the weight is up front,
Maybe on a diesel it is. I believe it is almost 50-50 on 35i. I also think it is normal for fronts to wear more on the outer edges as it handles the steering part of the job. I would be careful not to overinflated the fronts as you would not have the full contact while going straight. It isn't optimal.
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  #5  
Old 07-08-2012, 05:56 AM
lxs2bmw lxs2bmw is offline
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I asked my dealer about this when we were discussing the mileage out of the 20" Dunlops. They recommend over inflating by 2-3 PSI over what BMW recommends. My SA also said he follows the same practice on all of his BMWs as does the finance mgr with great success. They claim to not experience any abnormal wear on the tires. We were talking specific to the 20" wheel/tire combo by the way.

I plan to follow this practice this time around.
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  #6  
Old 07-08-2012, 06:54 AM
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ductman ductman is offline
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Quote:
Originally Posted by alexmish View Post
I am following recommendations, too, and seeing similar - more wear in the center... Mind that I do wheel alignments every 5k miles... Do you run 18, 19 or 20" tires?
I am running the 18in MIchelin, I will try running 32 front/ 34 rear as I never have a full load and at the most 1 in the back seat, my outer edges show no abnormal wear whatsoever , so I would assume that the rears are overinflated at 36 since the wear is more on the center.
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  #7  
Old 07-08-2012, 09:36 AM
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AutoUnion AutoUnion is offline
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OP, I think those are for a fully loaded car.

On my old Q7, the manual would recommend equal pressures all the way around (34 PSI) and then when it was fully loaded, they would switch to 38/42 PSI, with the rear having more PSI.
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  #8  
Old 07-08-2012, 10:04 AM
ard ard is offline
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Quote:
Originally Posted by davidc1 View Post
Maybe on a diesel it is. I believe it is almost 50-50 on 35i. I also think it is normal for fronts to wear more on the outer edges as it handles the steering part of the job. I would be careful not to overinflated the fronts as you would not have the full contact while going straight. It isn't optimal.
1. Are you referring to BMWs published specs WHICH ARE BASED ON A FULLY LOADED 35i?

I have no doubt it is close to that with 4 pax and the rear loaded with luggage.... if that is how your drive, then by all means use that in your calculus for tire pressure.

2. Yes, the fronts wear on the outside due to steering..... a bit more pressure up front mean the steering isn't preferentially wearing the edge but MORE of the middle of the tire is being used.

3. 'Not have full contact with the fronts while going straight'??? Please....

Quote:
Originally Posted by lxs2bmw View Post
I asked my dealer about this when we were discussing the mileage out of the 20" Dunlops. They recommend over inflating by 2-3 PSI over what BMW recommends. My SA also said he follows the same practice on all of his BMWs as does the finance mgr with great success. They claim to not experience any abnormal wear on the tires. We were talking specific to the 20" wheel/tire combo by the way.

I plan to follow this practice this time around.
Funny, huh? Everyone needs to experiment with what works for them with their CAR, their DRVING STYLE, their LOADS, and their TIRE TYPE. To pick "32" from BMW as a concrete recommendation is woefully inadequate.

A
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  #9  
Old 07-08-2012, 02:45 PM
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ductman ductman is offline
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I did some research model year 2007 thru 2013 X5, size 255/55 18

2007- 32/32 front and rear under 100 mph with full capacity
2008- """""""""""""""""""""""""""""""""""""""""""""""""""""""""
2009-"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
2010- 32/35 """""""""""""""""""""""""""""""""""""""""""""""""""""
2011- 32/35 even though my door sticker says 32/36
2012 32/36
2013-32/36

Why the difference in recommended tire pressure between model years with the same exact
spec tire ?
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  #10  
Old 07-08-2012, 04:12 PM
davidc1 davidc1 is offline
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[QUOTE=ard;6939828]1. Are you referring to BMWs published specs WHICH ARE BASED ON A FULLY LOADED 35i?

I have no doubt it is close to that with 4 pax and the rear loaded with luggage.... if that is how your drive, then by all means use that in your calculus for tire pressure.

2. Yes, the fronts wear on the outside due to steering..... a bit more pressure up front mean the steering isn't preferentially wearing the edge but MORE of the middle of the tire is being used.

3. 'Not have full contact with the fronts while going straight'??? Please....



Funny, huh? Everyone needs to experiment with what works for them with their CAR, their DRVING STYLE, their LOADS, and their TIRE TYPE. To pick "32" from BMW as a concrete recommendation is woefully inadequate.

A[/

Ok. Do what you want. I prefer to follow recommendation by mfr. I also thought outer edges of modern high performance tires were mainly responsible for cornering work. So proper inflation, whatever you believe that is, should be critical.
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  #11  
Old 07-09-2012, 01:56 AM
jadatis jadatis is offline
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Tire-pressure advice is all about load and speed , and a bit about camber-angle( alignment).
I once got hold of the formula that the tire-makers use and worked it out in spreadsheets.
Here a link to my public map of Skydrive that belongs to my hotmail.com adress with the same username as in this forum ( so you can mail me direct, spamm machines cant figure this out... I hope).
https://skydrive.live.com/?cid=a526e...E092E6DC%21128
Between the Dutch maps also many in English so for you to use.
If you use my recalculating spreadsheet, you will find low pressures on the back for normal use, even lower then the front. This normal use is what in Europe was given before 2000 and was for 3 persons and a little load in the car. They dont give that anymore after 2000.
So it is yust what tire-makers fill in the formula for load and speed.
Protocol has chanched after 2000 , and I think it has to do with the Ford-firestone Affaire.
But this does not mean that tires or roads have chanched after that, so you can still calculate with the European formula, wich is save for standard load and XL tires.
Tires with low aspect ratio ( The 40 in 255/40R18 for instance) though are probably calculated to high in their maximum load, I concluded and got confirmed by someone who worked for a tire-maker. So for those tires ( you probably have them) you have to use a higher pressure for savety of the tires. But then even , if you include that , you can go lower for the rear, and the middle -wear proves it.
But mind you dont confuse this with wear on only one side of the tire, look again .
If you give the sises of the tires and the maximum load and tirekind, I will look up the Aspect ratio in the graphics I got for percentage deflection measured when maximum load and reference-pressure on the tire, and calculate howmuch the referencepressure( further Pr and is 35psi for Standard load and 42psi for Extraload/XL/reinforced) has to be highenend up in the formula . If you also give the GAWR front and rear and the maximum speed of car , and the old advices of the book for normal use, I can do it for you , and give a balanced advice for normal use, for best gripp and comfort, and still save for the tires.
With these low AR tires though , the comfort and gripp will be bad , but savety first.

Greatings from Holland ( so sorry for wrong words and miss-spellings)
Peter
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I live in Holland and once got hold of the system the tire- and car manufacturers use to determine the advice-pressure for cars. Learned myself Excell to make spreadsheets for it.
Next link leads to map with spreadsheets to re-calculate advice pressures for non-OEM tires, or to check the original.
http://cid-a526e0eee092e6dc.office.l...0tyre-pressure
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  #12  
Old 07-10-2012, 07:07 PM
RockChips RockChips is offline
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So on a less than fully loaded car, do you want more or less tire pressure?

I'm not understanding...
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  #13  
Old 07-12-2012, 12:57 PM
jadatis jadatis is offline
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@ Rockchips
Lower loads may have lower pressure.
Less then a fully loaded car needs lower tire-pressure .
But problem is , that weight is mostly judged to low, so weighing is the only shure thing.
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I live in Holland and once got hold of the system the tire- and car manufacturers use to determine the advice-pressure for cars. Learned myself Excell to make spreadsheets for it.
Next link leads to map with spreadsheets to re-calculate advice pressures for non-OEM tires, or to check the original.
http://cid-a526e0eee092e6dc.office.l...0tyre-pressure
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