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Old 3rd July 2000, 22:17   #1
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Tire Pressure

Yes, I know its been covered by others- yet there seems to be no definitive answer to the question: what are the recommended pressures? (Im asking for the USA, but Im sure others are curious also)

I have dunlap 8080s and the sidewall says max pressure is 51psi. The sticker on the drivers side of the door has icons that apply to the dunlap tires but then says max=44/48. The sticker then lists another set of numbers but these have French next to them for a description. It seems to me that these are for snow tires.

I checked the M5 manual and it states recommended pressures should be 35/38. I called my dealer and was told to use 32/39. I then called BMW USA and they said to use whatever the door sticker says. I decided to call the dealer one last time and they then said to use the 44/48 number.

I tried this and it seems too high to me. The car is a little too "bouncy". I decided to compromise between the manual and the door sticker and set the pressures to 40/43.5 psi.

Does anyone know what the actual recommended pressures are?

thanks in advance.

ME
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Old 3rd July 2000, 22:41   #2
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i too am confused. same tires as yourself

i just dealt with this this morning in fact and hit the same exact information you did (the door panel -vs- the manual).

i ended up going with the door panel 44/48. it is definitely a high number. i don't know about "bouncy" but it's definitely different. my tires were something like 36/40. i actually turned off DSC a few times today because i thought it was engaging too easily.

i'm not averse to the 44/48 inflation (yet), but it's definitely different.

it'd be great to get some definitive info on this.

fwiw, i got the impression that the 44/48 was for a fully-loaded 5-passengers-plus-luggage scenario. however, i didn't see meaningful info otherwise, so stuck with it.

shawn
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Old 3rd July 2000, 23:22   #3
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Try the higher pressures(44/48) at first then watch the tires. If they wear in the middle of the tread reduce the air pressure for a while till they even out then add back air to less that the original pressure(40/44).

I tend to use higher pressures with high speeds and faster cornering manuvers. Keeps the rubber on the rim.

Had to go to Orlando a few years ago in a 535is, a distance of 160 miles and new I would be running at 80 to 90mph. The night
before a added seven pounds of additional air to each tire.

Sure enough at about 80mph I hit a giant turtle about six inches thick. I kept going another 1/2 mile to survey the damage under a
bridge overpass. A trooper was giving a ticket to a driver and I called to him to ask if he saw the turtle on the road and he suprised me by admitting he saw the turtle. So much for highway safety!

My factory wheel was bent about a 1/2 inch and the tire was secure and not leaking. I drove another 50 miles on it until I have the
opportunity to change it at a service station.

I believe that the higher pressure in the tire save the day. I could be wrong, you be the judge.

Jim
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Old 3rd July 2000, 23:28   #4
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Thanks for the replies. I tried the 44/48 and I just didnt like it that much and the wear was definately not spread out across the tires. I understand your point about higher pressures, but whats really confusing me is that usually the automaker has a "recommended" pressure and here I cant seem to get a straight answer. I always had my previous auto with the recommended pressures and I enjoyed great ride/handling and also got many more miles than friends with the same car but insisted on filling the tires to the max allowed by the tire maker.

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Old 3rd July 2000, 23:59   #5
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They recommended 44/48 psi in the tires when I was at the Spartanburg program.
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Old 4th July 2000, 03:04   #6
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Anzir:

Did they say why or under what conditions?

I just pumped mine up, so no data on uneven wear. Can anybody here comment on uneven wear at the mfg. recommended pressures?

Shawn
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Old 4th July 2000, 18:00   #7
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My 2 cents worth... I have the Dunlop 8080e's and I too got all the conflicting info. The car came from the dealer with 38/42. This was a little too soft for my liking and after consulting with them, I raised the pressures to 42/45. This seems to be a good compromise as the car handles well at high speeds and corners well too. The ride stiffens up a little and this is great in my opinion. This IS a sports car!

I ran the tires for a week at 45/48 and while the steering feel gets a little lighter, I felt I didn't need that harsh of a ride. True, the traction control engaged with hard acceleration or agressive cornering. Everyone I talked to says keep them above 40 all around. I agree. Watch for uneven wear, especially on the front tires. If you corner agressively, increase the pressures into the mid to upper 40's. The Michelins should run the same way. The car manual does not know what brand of tires (ie the rating)that will be put on the car and most likely has a wide safety margin built in. The door sticker is much more accurate. The local Dunlop dealer said to run them as high as you can stand up to the maximum if doing serious performance driving, however said to back them off at least a few pounds for everyday driving. They do a lot of high performance cars and seemed to know exactly what the answer was.

Has anyone ever asked this question at the driving school?
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Old 5th July 2000, 05:58   #8
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Shawn,

They said for every-day use and even at the track, they said that the higher pressures give the car a better feel and allow for better handling. I don't recall the specifics of exactly how and why. Those are the pressures that they had all the M5s there at Spartanburg. Also, this is just a little bit of a side-note, but I spoke to the instructors there, and they said that once the cars finish their stock set of tires (whether Michelins or Dunlops), they are all put on Michelin Pilot Sports.
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Old 5th July 2000, 16:03   #9
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I find that a compromise between the manual and the door pressures works great. Even handling and wear. I use 35/38. These pressures are closer to the norm of other very low profile performance tires I've had (porsches, ferrari, MBZ).
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Old 7th July 2000, 01:00   #10
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I thought Id chime in- I saw that the fronts are wearing well at 40psi, but theres about 1/2 inch on the sides of the rears that arent getting much wear, so I decided to drop it down to 42psi. The car seemed to ride better this way. Ill leave it at that for a few days.

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