Air pressure

[shortseller]

Guys & Gals,

What air pressure are you running in those 19"?

I see the label inside the front door listing 32/32.

When I picked up my car after the dealer prep, they had like mid 40s +/- 3 which surprised me when I got home and checked them the next morning after sitting over night, for a cold reading.

Set them at 32 psi respectively, like the ride but am I at risk of uneven or premature wear?

Thanks

[thebishman]

The manual clearly states that 31psi is the recommended pressure at all four corners for lightly loaded, less than 115 mph circumstances iirc.
Bish

[robbo mcs]

Mine was at around 40 from the dealer as well, and it did not feel right. I've changed it to 32 cold and the car feels a whole lot better. The pressures generally run around 35 when hot.

As far as I'm concerned it is a performance car, and so I'll set the pressures at the recommended level, which gives the best performance. That may or may not be the best for tire wear, but for me that doesn't really come into consideration for this car.

[shortseller]

^Thanks guys! 31/32 it is, and yes it did feel much better than in the 40s.

[MaynardZed]

I run about 36 around town with the PSS. At the track, I'd start with about 27-28 cold which would be about 34 coming off hot.

[JeffM-Houston]

At the track, I'd start with about 27-28 cold

That seems way too low to me. In my first autocross I ran my stock front PSS tires at 36 psi cold, and was still getting a little too much roll over on the sidewall.

Anyway, when I got my car the tires were set at 40 from the dealer. When I checked everything a couple of days later I reduced them to 32 all around. When I picked my car up after the 1200 mile service the dealer had it back to 40 all around, and I put them back to 32.

[slats1279]

Anyone have any more thoughts on why the dealers are not inflating according to the recommendations? This has happened to me twice.

First time was a few months ago after picking up my wife's X3. One week later she had low tire warnings on all wheels. Outside temp had dropped some, but not enough to account for the 10+ psi underinflation in all wheels. I corrected things and have had no issues since.

A few weeks ago I picked up my F80. Noticed today during a routine tire pressure check on all vehicles that all tires on it were in the 40's. Temp has dropped a fair amount since I picked the car up, so was likely even further inflated upon delivery.

Are they going by some other guidelines or are they just careless? I'm guessing the latter.

Thoughts? Thanks.

[01ON19]

Originally Posted by slats1279

Are they going by some other guidelines or are they just careless? I'm guessing the latter.

Thoughts? Thanks.

Well, either they know better than BMW or they are careless. I think you have your answer.

[Aralan]

My car was delivered to me with high tire pressures also. I dropped to around 32 PSI cold. I'm seeing 33.5-34 PSI in normal driving. For track I'll probably start at 27 PSI cold.

** Cold = mid Fall garage temperature which is around 50 degrees. My garage isn't temperature controlled, but my mechanical room where the furnace and water heaters are located is directly behind it, so the garage is a bit warmer than outside.

[thebishman]

Originally Posted by slats1279

Anyone have any more thoughts on why the dealers are not inflating according to the recommendations? This has happened to me twice.

First time was a few months ago after picking up my wife's X3. One week later she had low tire warnings on all wheels. Outside temp had dropped some, but not enough to account for the 10+ psi underinflation in all wheels. I corrected things and have had no issues since.

A few weeks ago I picked up my F80. Noticed today during a routine tire pressure check on all vehicles that all tires on it were in the 40's. Temp has dropped a fair amount since I picked the car up, so was likely even further inflated upon delivery.

Are they going by some other guidelines or are they just careless? I'm guessing the latter.

Thoughts? Thanks.

Thy might believe that inflating the tyres to such a high psi prevents flat spots if the car is parked for a while?

[MaynardZed]

Originally Posted by JeffM-Houston

That seems way too low to me. In my first autocross I ran my stock front PSS tires at 36 psi cold, and was still getting a little too much roll over on the sidewall.

Anyway, when I got my car the tires were set at 40 from the dealer. When I checked everything a couple of days later I reduced them to 32 all around. When I picked my car up after the 1200 mile service the dealer had it back to 40 all around, and I put them back to 32.

Time on track. Autocross session much shorter than my 20 minute HDPE sessions on road course. Not as much time to heat up / overheat the tires. Also referring to R888 that I was running which has stiffer sidewall than PSS.

Anyway, back to the track this Saturday with the M4, can't wait!

[Aralan]

I've finally gotten some openings to push the car a little more, and I'm feeling that the tire pressures may be a little off, the car feels a little sloppy at the limit. I'm seeing 33.5-34 in most of my driving which may be a little on the low side. I'm going to try going up 1-2 PSI and see how it feels then.