[M2siast]

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I had been suffering from high fuel consumption, highway wandering (had set M2 to Sport+ chassis to firm up the drive and control the wandering), and very poor wet grip (Pirelli Pzero).

I noticed my car came with 32 psi all around… and I’m not sure why BMW would do that…

I have since corrected my tire pressure to
- 40 front
- 45 rear (I like to put 1 psi over because I inflate them in a warm garage, and it’s getting cold out, so it accounts for the loss of pressure coming out of the garage)

Now my car:

- is great on the track (already was)
- feels lighter
- has better turn in (I thought the turn in was great before, oh what I missed, the sharpness is amazing now)
- has unbelievable wet grip (no slide whatsoever; whereas before I couldn’t really use throttle and turning was sketchy because of the loose rear)
- has better fuel economy (combined with me changing gas from Shell to Chevron, which I expected)
- has a sportier ride without being uncomfortable

Any guesses as to why BMW would set the pressure so low?
What are you guys running and have you played with the different tire pressures?

I’ll stick to this recommended setting for good.

[aerobod]

Originally Posted by M2siast

I had been suffering from high fuel consumption, highway wandering (had set M2 to Sport+ chassis to firm up the drive and control the wandering), and very poor wet grip (Pirelli Pzero).

I noticed my car came with 32 psi all around… and I’m not sure why BMW would do that…

I have since corrected my tire pressure to
- 40 front
- 45 rear (I like to put 1 psi over because I inflate them in a warm garage, and it’s getting cold out, so it accounts for the loss of pressure coming out of the garage)

Now my car:

- is great on the track (already was)
- feels lighter
- has better turn in (I thought the turn in was great before, oh what I missed, the sharpness is amazing now)
- has unbelievable wet grip (no slide whatsoever; whereas before I couldn’t really use throttle and turning was sketchy because of the loose rear)
- has better fuel economy (combined with me changing gas from Shell to Chevron, which I expected)
- has a sportier ride without being uncomfortable

Any guesses as to why BMW would set the pressure so low?
What are you guys running and have you played with the different tire pressures?

I’ll stick to this recommended setting for good.

On the track a higher hot pressure with most tyres will help reduce camber wear on the outside edge and give more even grip across the tread as the tyre is scrubbing, but on the road it may reduce the tyre life quite a bit by wearing out the middle of the tread.

Better wet grip in a straight line with a higher pressure is generally a result of a narrower contact patch, but may make the car less stable at the limit.

I would keep an eye on the wear patterns, as you may only get half the life out of the tyre as it approaches the maximum pressure on the tyre sidewall, compared with a pressure that gives even tread wear across the width for normal use.

I generally run a bit higher pressure than recommended (at the moment 2.3 bar / 34PSI), but eventually find a pressure that works best for me from a combination of grip and even tyre wear. With our old M240I, anything higher than 2.4 bar (35PSI) would wear the middle out prematurely, especially with winter tyres.

[KevM2]

I also thought 32 this was strangely low but when I go over 36 the steering feels more numb and the car feels a little too rough on bumpy roads.

[M2siast]

Originally Posted by aerobod

On the track a higher hot pressure with most tyres will help reduce camber wear on the outside edge and give more even grip across the tread as the tyre is scrubbing, but on the road it may reduce the tyre life quite a bit by wearing out the middle of the tread.

Better wet grip in a straight line with a higher pressure is generally a result of a narrower contact patch, but may make the car less stable at the limit.

I would keep an eye on the wear patterns, as you may only get half the life out of the tyre as it approaches the maximum pressure on the tyre sidewall, compared with a pressure that gives even tread wear across the width for normal use.

I generally run a bit higher pressure than recommended (at the moment 2.3 bar / 34PSI), but eventually find a pressure that works best for me from a combination of grip and even tyre wear. With our old M240I, anything higher than 2.4 bar (35PSI) would wear the middle out prematurely, especially with winter tyres.

I would agree if I were using a pressure much higher than recommended. But the recommended pressure is 39F/44R…

I know it manages heat better too.

Hard to have such a large discrepancy for putting around town at 32 and 44 for highway driving…

Originally Posted by KevM2

I also thought 32 this was strangely low but when I go over 36 the steering feels more numb and the car feels a little too rough on bumpy roads.

It can get bumpier if on harder shock settings. Did you try comfort? As I went even higher it helped the car settle even more.

[aerobod]

Originally Posted by M2siast

I would agree if I were using a pressure much higher than recommended. But the recommended pressure is 39F/44R…

At any load up to the maximum and speeds up to 160km/h my door placard and the owners manual show 32F/32R with 275/35-19 front and 285/30-20 rear tyres.

For speeds over 160km/h the owners manual shows 33F/38R for full load without M Driver's Package and only 39F/44R with M Driver's Package, likely to ensure tyre integrity over tyre life at 285km/h with a full load of 4 passengers and luggage.

[GT3M2]

40/45 is WAY TOO high.

-GT3M2

[RandomBro]

My car came with 38 PSI cold, but that is for cars with M driver package that raises the speed limiter.

As soon as I lowered it back to the recommended 32PSI car became noticeable more alive, SO much more feedback than the junk 38 PSI.

I can only imagine 40 PSI cold to make the car drive like doo doo IMO.

[RandomBro]

Originally Posted by GT3M2

40/45 is WAY TOO high.

-GT3M2

Agreed 100% makes no sense, unless u like driving lexus type vehicles.

[RandomBro]

Originally Posted by M2siast

I would agree if I were using a pressure much higher than recommended. But the recommended pressure is 39F/44R…

I know it manages heat better too.

Hard to have such a large discrepancy for putting around town at 32 and 44 for highway driving…



It can get bumpier if on harder shock settings. Did you try comfort? As I went even higher it helped the car settle even more.

Door sticker is 32 for me? 38 is for cars that can achieve higher max MPH via M driver pack.

[M2siast]

Originally Posted by RandomBro

Door sticker is 32 for me? 38 is for cars that can achieve higher max MPH via M driver pack.

The door placard only shows one pressure. Which is the first time they do that from memory. Every other BMW I had had the correct pressures in the placard, not just one.

So, they’re only listed in the manual and in the MyBMW app (which adjusts based on which tires you select in iDrive).

[aerobod]

This is the info I have for the placard and owners manual:

[Chris13002]

32 psi it is! Thanks guys! Thought I was off on my car with P-Zero's also.

[RandomBro]

Originally Posted by aerobod

This is the info I have for the placard and owners manual:

I have the same

[Zatellia]

So mine came from the dealer at 35 front and back, the BMW app "recommended 33.9 front and back. How does the app calculate its recommended psi, does it use avg speed + tire size? Curious if anyone knows

[M2siast]

Originally Posted by Zatellia

So mine came from the dealer at 35 front and back, the BMW app "recommended 33.9 front and back. How does the app calculate its recommended psi, does it use avg speed + tire size? Curious if anyone knows

The app picks up from the tire choice you make in iDrive.
If they’re cold, the app will recommend 32 psi, if you choose 19” summer tires for less than 160 km/h.
When you drive, tires get warmer, the app adjusts for the temperature.

Best is to set the baseline after not driving the car to ensure tires are as cold as possible. Then the recommended psi will always match what the tires have (32 cold, 35 hot, for example). Don’t try to set the pressure based on hot tires because the app is not updated real time, and because tires raise temperature differently and individually, so when driven, the car will ask (and report) different tire pressures per tire (e.g. 34 front left, 33 front right).

[M2siast]

Originally Posted by Zatellia

So mine came from the dealer at 35 front and back, the BMW app "recommended 33.9 front and back. How does the app calculate its recommended psi, does it use avg speed + tire size? Curious if anyone knows

Here’s what it looks like, to illustrate what I mean. This is my car.

[M2withACC]

.

[Zatellia]

Originally Posted by M2siast

Here’s what it looks like, to illustrate what I mean. This is my car.

Oh I'm familiar with the app, I was just wondering how it calculated the recommended psi; average speed, temperature, type of tire, ect

One side of my car is parked in the sun and one side is in the shade lol

[ftjack]

I have no problem driving with 32 psi cold front and rear. I understand raising pressure a bit for road driving is fine as it saves a bit gas though make your car feel stiffer. But I have to say 40/45 psi is way too high, and for track driving, I thinking common practice is lower the tire pressure instead of raising the pressure? I know people warm up tires on track and lower the pressure to recommended value (i.e. 32 psi hot instead of cold). Many of them lower it even more. Low tire pressure gives you more contact area with track surface and improves handling.

[RockCrusher]

Originally Posted by M2siast

I had been suffering from high fuel consumption, highway wandering (had set M2 to Sport+ chassis to firm up the drive and control the wandering), and very poor wet grip (Pirelli Pzero).

I noticed my car came with 32 psi all around… and I’m not sure why BMW would do that…

I have since corrected my tire pressure to
- 40 front
- 45 rear (I like to put 1 psi over because I inflate them in a warm garage, and it’s getting cold out, so it accounts for the loss of pressure coming out of the garage)

Now my car:

- is great on the track (already was)
- feels lighter
- has better turn in (I thought the turn in was great before, oh what I missed, the sharpness is amazing now)
- has unbelievable wet grip (no slide whatsoever; whereas before I couldn’t really use throttle and turning was sketchy because of the loose rear)
- has better fuel economy (combined with me changing gas from Shell to Chevron, which I expected)
- has a sportier ride without being uncomfortable

Any guesses as to why BMW would set the pressure so low?
What are you guys running and have you played with the different tire pressures?

I’ll stick to this recommended setting for good.

BMW sets the tire pressures based on max speed, load, and package and wheel/tire combinations. I'm sure BMW receives some input from the tire makers and does some field testing: track and road; to ensure the tires do not manifest any abnormal (side wall or center) wear under varying speeds and load conditions.

32psi is not low for those of us owners that have the tire/wheel setup for which 32psi is the recommended pressure. Oh, and keep the speed below 100mph...

40/45 is way high unless you are carrying the Olympics weight lifting team on a run around the 'ring...

Or you have the M package and are running 285/30 20" and 295/20 21" tires. At >100mph the manual calls for these to be inflated to 44psi and 48psi respectively.

My car doesn't have the M package and has the 19"/20" tire combo and I don't but very seldom and then not for but just a brief instant or two take the car above 100mph.

Thus I follow the owners manual -- which someone has already posted -- and for my car/tires it is 32psi "cold" provided 100mph is not exceeded. (If I drove my car fully loaded or tracked my car I'd certainly check the owners manual for how much pressure to run fully loaded or if I exceeded 100mph for any significant time.)

With 32psi is the tires I don't notice any issues. Gas mileage is reasonable. Really though the tires would have to be considerably under inflated to affect gas mileage. Far and away the biggest factor in gas mileage is vehicle usage.

The ride is firm but not jarring or harsh and the tires even when I press the car on curvy roads manifest considerable grip.

Unless you are running tires for which BMW calls for higher inflation pressures and the pressures you have selected are within BMW's recommended pressure with the tires inflated as high as you have then inflated I would expect sub-par contact of the tread to the road. And I would expect after awhile the tires to show excessive wear in the center of the tread.

[c1pher]

Originally Posted by M2siast

I would agree if I were using a pressure much higher than recommended. But the recommended pressure is 39F/44R…

I know it manages heat better too.

Hard to have such a large discrepancy for putting around town at 32 and 44 for highway driving…



It can get bumpier if on harder shock settings. Did you try comfort? As I went even higher it helped the car settle even more.

My door placard says 32 psi. What are you referencing to get 39/44? With that said, I noticed my tires from the dealer were set to 36 all the way around.

[c1pher]

Originally Posted by RandomBro

My car came with 38 PSI cold, but that is for cars with M driver package that raises the speed limiter.

As soon as I lowered it back to the recommended 32PSI car became noticeable more alive, SO much more feedback than the junk 38 PSI.

I can only imagine 40 PSI cold to make the car drive like doo doo IMO.

I have the M driver package and my door placard says 32PSI.