[BarryJI]

The car is a blast; I am thrilled with it.

I would greatly appreciate your advice on the following:

- Tires: the manual lists a huge array of possible tire combos. I believe I have run-flats on the 18" wheels that the M Sport comes with and I will look at the specs on the tires themselves tomorrow but can anyone who knows for certain tell me what these tires are and what is the optimal PSI, cold, front and rear? I think the dealership might have over-inflated them.

- Ventilation: There is a small glitch in the ventilation directional settings where the passenger-side mode selection will not cycle to the upper, middle and lower combo (but the driver-side settings will). I can get every mode for the passenger side except the three-direction output described above. As the car is brand new I feel I should have the service dept. address this but does anyone know how big of a deal it might be to fix it? Is it just a programming glitch that can be reset, or do you think it's a more complicated mechanical issue?

Many thanks.

[mfourn20]

Tire inflation is on the drivers side when you open the door. For the staggered bridgestone run flats I believe its 32psi front 38psi rear.

Only the drivers side will select the defrost on the windshield...and then of course there's the super defrost button as well.

[rjroch]

Is it just me or does 32/38 f/r seem odd for a 52/48 f/r weight distribution?

Everything else I've owned has had a bit more pressure at the heavier end of the vehicle, not a lot more at the lighter one.

[Uridian]

The 228i is closer to 50/50, but that is beside the point.

Anyway, I too was a little surprised about more pressure in the rear, because of the same conventional wisdom.

However, almost all of my previous cars have been FWD with a square setup. I wonder if the RWD staggered has different tire pressure requirements. I'd be curious to see what the door sticker said on 228/235's with square all seasons vs staggered summers.

[bimmerfile]

OP;
My BMW dealer always fills the tires of every BMW they sell with nitrogen, so if your tires are nitro inflated, then you probably should not further inflate them with air. Go back to the dealer if you want to change the pressure..

[2msport]

Originally Posted by mfourn20

Tire inflation is on the drivers side when you open the door. For the staggered bridgestone run flats I believe its 32psi front 38psi rear.

Only the drivers side will select the defrost on the windshield...and then of course there's the super defrost button as well.

he is correct

[Zooks527]

Originally Posted by bimmerfile

OP;
My BMW dealer always fills the tires of every BMW they sell with nitrogen, so if your tires are nitro inflated, then you probably should not further inflate them with air. Go back to the dealer if you want to change the pressure..

Uh, no.

Regardless of what is in your tires at the moment (straight air or pure nitrogen), it doesn't make a whit's worth of difference whether you correct the pressure with air or nitrogen.

Well, I suppose that since someone will try to charge you extra for putting in nitrogen, that would be a difference.

[Cyberdemon]

Good news everyone, air is 78% nitrogen - it's like 80% of the value for free!

I remember a dealer once telling my wife she was being irresponsible for her safety by putting "air" in her tires.

[2msport]

Originally Posted by Zooks527

Uh, no.

Regardless of what is in your tires at the moment (straight air or pure nitrogen), it doesn't make a whit's worth of difference whether you correct the pressure with air or nitrogen.

Well, I suppose that since someone will try to charge you extra for putting in nitrogen, that would be a difference.

Correct. Even though there might be benefits of going with pure N2, it's makes no difference in safety to mix. Nor is it worth the money to spend on N2. If it's free then do it.

[Cyberdemon]

Originally Posted by rjroch

Is it just me or does 32/38 f/r seem odd for a 52/48 f/r weight distribution?

Everything else I've owned has had a bit more pressure at the heavier end of the vehicle, not a lot more at the lighter one.

This is conventional wisdom, but it has to do with the handling characteristics of the car and the contact patch under load - adjusting the tire pressures accounts for adjusting the cars tendency to oversteer/understeer.

Remember that 52/48 is a static weight distribution and cars are not static creatures.

Under acceleration, the weight balance shifts to the back and braking the weight shifts to the front.

Staggered tires further complicate the issue since they provide increased traction in the rear which causes the car to naturally want to understeer.

The door placard is the manufacturers intended guidelines but as many of the guys here who go to the track can tell you, different tire setups and handling preferences will all impact the amount of pressure you want to run. BMW's tend to not have enough camber in front either which means if there isn't enough pressure in the front the tires will start to roll onto the sidewall under fast cornering.

[rjroch]

Originally Posted by Uridian

The 228i is closer to 50/50, but that is beside the point.

Anyway, I too was a little surprised about more pressure in the rear, because of the same conventional wisdom.

However, almost all of my previous cars have been FWD with a square setup. I wonder if the RWD staggered has different tire pressure requirements. I'd be curious to see what the door sticker said on 228/235's with square all seasons vs staggered summers.

I was quoting 52/48 because I have a M235i, on 4 identical Pirelli Cinturados. It, too, is 32/38.

[BarryJI]

Thanks for all the wise counsel, gents, much appreciated, especially the information about the directed vent settings; I would have felt very foolish, taking the car back to BMW to address this.

As for the tires, the iDrive app shows psi in the high 30s cold when the placard calls for 32F/38R so they may have been over-inflated at the dealership. I am pretty sure they have not been filled with nitrogen...

Re. tire pressures, since it is often impractical to fill/adjust pressures when the tires are cold, does anyone have a rule-of-thumb for how to adjust the numbers on the door placard for cold pressure numbers when the tires are warm?

[rjroch]

Originally Posted by BarryJI

Re. tire pressures, since it is often impractical to fill/adjust pressures when the tires are cold, does anyone have a rule-of-thumb for how to adjust the numbers on the door placard for cold pressure numbers when the tires are warm?

What I do is check the pressure cold, then check the pressure warm. That gives you a rough idea of what the differential will be, so you know how much to inflate.

Example:

Tire is 30psi cold, 36psi warm, and needs 32psi. Inflate warm to 38-40psi, should settle out closer to 32. Obviously this is not an exact science.

If you lack an air compressor in your home garage you could also overinflate a few pounds extra at your gas station. This won't do any damage especially in the short term. Once the tires are cooled off, deflate to the desired pressure.

[Cyberdemon]

Originally Posted by BarryJI

Re. tire pressures, since it is often impractical to fill/adjust pressures when the tires are cold, does anyone have a rule-of-thumb for how to adjust the numbers on the door placard for cold pressure numbers when the tires are warm?

Tires are not that picky, especially in daily driving.

As long as the tires are generally consistent and in the ball park you'll be OK.

The easiest thing to do is get a $5 tire pressure gauge (one of the better ones with a real dial tends to work better than the cheapo popout pen gauges) and check the car before you go for a drive.

If you know you need to add 3psi to the tire, just add 3PSI to the tire hot. It will be close enough.

If you are tracking the vehicle then you can start worrying about adjusting the hot pressure to tweak the driving dynamics of the car.

[Uridian]

While I agree with Cyberdemon, I still ordered this:

http://www.amazon.com/Black-Decker-A.../dp/B000IE0YIQ

It's easy enough to just note how low your tires are and fill accordingly at the gas station, or I can just check every now and then and top up as needed in my driveway.

[Cyberdemon]

Originally Posted by Uridian

While I agree with Cyberdemon, I still ordered this:

http://www.amazon.com/Black-Decker-A.../dp/B000IE0YIQ

It's easy enough to just note how low your tires are and fill accordingly at the gas station, or I can just check every now and then and top up as needed in my driveway.

An air compressor is an invaluable man tool. If you don't have room for a big compressor (air tools FTW) then a little guy like this is nice to have. I actually have one thats much smaller and runs off the car's 12v in case you need to fill up on the road. It used to fit in the little cubby under the trunk on my F30. Would take a while to fill up because of how small it was but it'd do the trick.

[Zooks527]

Originally Posted by Uridian

While I agree with Cyberdemon, I still ordered this:

http://www.amazon.com/Black-Decker-A.../dp/B000IE0YIQ

It's easy enough to just note how low your tires are and fill accordingly at the gas station, or I can just check every now and then and top up as needed in my driveway.

I have the same one.

Well, I guess "had" would be more accurate now. Ever since she had a "low tire" light come up on her Subie, my wife keeps it in the back of her car. If I use it for anything around the yard or on my car, she's quite insistent it end up back in hers.

[BarryJI]

I've never had one, although I've been tempted. The one linked on Amazon looks robust and good value for money. I guess I've always wondered if I'd actually use it vs. tooling down the street to the gas station with the industrial-strength compressor.

[Viffermike]

Originally Posted by Uridian

While I agree with Cyberdemon, I still ordered this:

http://www.amazon.com/Black-Decker-A.../dp/B000IE0YIQ

It's easy enough to just note how low your tires are and fill accordingly at the gas station, or I can just check every now and then and top up as needed in my driveway.

Gads: that thing is expensive. I have a $20 one from Pep Boys (a "Bell", I believe) that is about the size of a paperback college textbook and does the same job commendably. I don't keep it in the car, but it comes in handy for pressure adjustments at home.

[2msport]

If anyone is looking for a fantastic tire pressure gauge this is it. It was recommended from tire rack .com

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

It has a metal tip that seals well and makes getting a good reading super easy. (with no air leakage) Also has a trigger on the bottom to let air out to get the exact pressure set. It beeps after each reading so you know it's done. Has a nice lit screen and feels very nice in the hand. I believe its size and shape makes for getting good readings.

I do believe all gauges are NOT created equal. I replaced a $8 cheapo with this thing, and it's a dream to use. Is it accurate? I hope so. But who can really know when a reading is accurate? You're at the mercy of the device and I doubt any one has a daily checked quality controlled gauge.

Always check the pressure in the morning before any sun hits the tires and before driving. Ambient temps affect the PSI. The rule of thumb is for every 10° Fahrenheit change in air temperature, your tire's inflation pressure will change by about 1 psi (up with higher temperatures and down with lower).