Good feature nonetheless since every 10F change in temperature, tire pressure typically changes by about 1 PSI.

 

I'm not familiar with BMW display options, but I don't think there's any difference between the BMW and Mercedes pressure monitor systems.

I think you are talking about BMW displaying current tire pressures and temps, but they are "actual, live," not "dynamic recommended values."
You can have the same display on your MB.

Recommended tire pressures don't change depending on weather or outside temperatures, and I can't think of a reliable algorithm that could estimate the vehicle's loading and translate that into a recommended tire pressure. (Someone correct me if BMW has implemented this.) (I can only see problems doing this, such as Ford and Firestone in the '90s.)

Even though the gas flap states different pressures for different loads and speeds, those recommended pressures are to be set/measured at the international standard of 20°C, AKA 68F.

The recommended pressure "expects" the pressures to rise as the tire warms up, and it's NOT recommended to air down or up as the tire temp changes.

The doorpost stickers are confusing because some bureaucrat in DC required those stickers. But they are not specific to the CAR, with its specific equipment. They are specific to the TIRES' pressures, no matter what car they are mounted on.

Mercedes goes one step further and adds the gas flap sticker which is specific to the car equipment and the tires.

It's confusing because the FED required labels on the doorpost, and people generally don't understand them, and Mercedes adds yet another sticker.

But in reality it's simpler:
Assess your load, decide whether you have winter tires, and inflate your tires while cold.

Set your display to watch your tire pressures if you want, but it's not necessary because the TPMS will alert you to loss of pressure. Same as BMW.

(Edit: this reminds me of the reasons that car manufacturers switched to "idiot lights" in the '50s. People were accusing manufacturers of Penny pinching, but in reality it was because service departments were busy explaining how to read guages, which took up a lot of time and made customers angry.
Today you have the choice of seeing the display or not.)

 

Just looked up a video out of curiosity, I'm not sure of the model or year BMW shown in this video linked below but it appears to be the same info except it tells you directly on screen, the recommended TP (see relevant screenshots).

​​​​​​It does gives you an option to select/change tires. Not much of a discernible difference overall between the two systems IMO. Switching tire option is nice though if it allows you to select a wide variety of sizes, for example my summer wheels are 22s but my winter wheels are 20s. It took a decent amount of research to figure out the best TP when I switched to my 20" winter wheels. But are you allowed to select tires outside of what is recommended in the BMW system?



Screenshot from video showing tire selection

Screenshot 2 showing TP, doesn't appear to show temp but maybe temp is model specific


Edit: Answered my own question from above. If anyone is curious, this video does a deeper dive into tire selection with BMW idrive

You Tube

 

Interesting, looks like bmw does show the temperature recommended based on how many psi increased from when it was cold. So yes it does change the recommended inflation pressure when you drive it.

You win some you lose some for example with on board systems, MB shows transmission fluid temperature in amg models while bmw m does not show it.

 

Yes, the BMW tire recommendation changes w/the ambient temperature. This becomes important if you have a true 4 seasons and the winter is much colder than prior weeks (or even days) but you forgot to increase tire pressure to compensate!

 

I just spent some time on Bimmerpost.
I was wrong, BMW really does call their TPMS display "recommended."
I scanned a couple dozen threads, and the consensus was that it's nothing more than a TPMS display as I described above.
As the tire temperatures go up and the pressure's go up, you see it on the iDrive display.
All of the posts thought that even the concept was Goofy, because why would you pull over during your drive and change tire pressures? Like three to four times a trip?
The consensus was to use the doorpost sticker and ignore the iDrive recommended pressures.

MB goes one step further and gives you a gas flap sticker that you can read and just inflate your tires. Low tech, but better IMO, as well as the threads I read on Bimmerpost.

 

I've had my X3 for nearly 2.5 years and can tell you that no other car maker does this. Let me give you an example:

1) My X3 requires a min 33 psi up front and 36 in the back. I fill up tires to this pressure in Aug where temps can get close to 100°F.
2) December rolls around and temps are now closer to 30°F.
3) I've driven my car for well over an hour so tires are sufficiently warmed up and I check tire pressure. It reads 33 psi front and 36 psi back.
---- at this point, no other car make will give you a red flag as the absolute min pressures you input into the system has been met! ----
4) My X3 warns me my tire pressure is low because it has calculated what it should be with warmed up tires! Obviously if I had checked before I started driving, pressures would have been less than 33/36 psi!

My GLS doesn't do this and no other car make I know of does the above!

 

The video shows how far into the menu you have to go to set your TPMS pressures. That's all. The procedure is on p363 of the MB Owners Manual.

With MB, you just read the gas flap and inflate your tires.
THEN to go to the to menu to confirm, IF you made a significant change.

The advantage of BMWs iDrive input seems to be that you can change tire sizes (like 22" to 20" for winter) and you don't have to look up the pressures. It's the only advantage I can see. It may not even do that, though.

Just check your tire pressures monthly and adjust to the gas flap pressures.

You only need to reset your TPMS if you change tires or decide you want other than recommended tire pressures.

You SHOULD NOT Change inflation just because the pressure rises when warm. The Tire and Rim Association is specific about this. (Tire Regulatory body.)

It's just another solution in search of a problem.

Yes, the GLS does it but it doesn't call it recommended. BMW misses here.

 

They all do that. It's a Fed
requirement.
BMW just makes the display confusing. iDrive has been overly complicated and a subject of complaint for 40 years now.
You can have the same display on your GLS. It's just called "pressure," not "recommended pressure." It's a silly algorithm.

Be happy that you're not a BMW service advisor having to explain that display. There's no real way to explain it.

When I sold BMWs (80s) nobody in the store was able to explain iDrive satisfactorily to a customer. Every year we all hoped they'd abandon iDrive, yet BMW persisted. It just made customers confused and angry.

It's kind of like the first version of MBUX that confused a lot of people, so MB dumbed it down with v.2. Customers are much happier now and we see far fewer posts complaining about MBUX.

 

I'm curious, does your X3 show tire temps anywhere in the menu display? I didn't see tire temps like MB in any videos I saw online. Also, does your X3 still have a sticker for recommended TP for normal and load somewhere?

 

MB TPMS display at extreme tire temps...

Always displays the current pressure and temperature.

 

I'll check on my drive home. Tire pressures were only in iDrive so I would imagine temps are there too.

Sticker for X3 is only on the door jamb per NHTSA.

 

To my knowledge, the only manufacturer that shows load and speed pressures is Mercedes, on the gas flap.

I've only ever found one tire store that looked on the gas flap, because they don't expect any information to be there, based on other cars.
Discount Tire also uses the door post, and I have to correct them every time.
My car is not happy with the doorpost pressures.

 

Attached is a pic of my X3's tire pressure reading through iDrive (no tire temp reading).
Notice how it reads 32 psi front and 35 psi back but recommends 35 psi front and 38 psi back (tire temp before trip start should have been 33 psi front and 36 psi back)?
This was at the end of my commute so my tires were warmed up but haven't been pressured up since Fall at the latest!

 

Good reminder to fill them up. Thanks!

I'm surprised BMW doesn't show the tire temps.

 

Thanks.
Based on the previous video, am I correct that the recommendation 35 psi front and 38 psi back can only be reset through the menu by selecting tire size and winter/summer?
What if you decide that +2 is your preferred pressure, and you'd like that to be the Recommended pressure?

What I do with the GLE is to inflate to the pressures I want, then go to the menu and "Accept this as the new pressure," or similar wording, after I get rolling for a bit and the readings populate.

 

The type of tire (winter/AS vs summer) really only gives you a default starting tire pressure. The minimum cold tire pressure can always be set in iDrive but the dynamic pressure (after the car has been driven) can't be changed by the user.

My current preferred setting is 33 psi front and 36 psi back per the sticker. If I had changed it to say 35 front and 38 back, then the recommended dynamic pressure (after being driven) would have been ~2 psi higher than in my current picture!
The car does all the math for you (which is appreciated by me as an engineer w/a good understanding of thermodynamics) so that if there is a shortage in pressure while you're driving, you can check the cold tire pressure when the tires cool down.
It was 22°F this morning so my pressure being off by about 3 psi may come back to haunt me if I don't address it soon!

I can geek out on this as an Engineer but I do understand things have to be "dumbed down" for the general masses and the most likely reason why no other car maker does this!

 

I Geek Out on tire pressure as well. I have air in the garage, and I check pressures monthly with a calibrated, altitude-adjusted gauge. (in addition to having the TPMS/Temp display alive at all times).
I am well aware that sunny side tires can be +10*F and pressures +3-5psi on that side. And the gain in both, at 80mph. Or the decrease if I park in 0*F temps for a couple of hours.
That's why I approximate the 68*F standard when I inflate, and the pressures behave as expected, just as Boyle's Law predicts.
All that's good for me, and I record tread depths across the tread every few thousand miles, to correct for unexpected wear patterns.

Based on your description of the BMW iDrive approach, I think I'd be checking pressures more, trying to second guess their algorithm. I.e. waste of time.
Later, I think I'd want to shoot it.

It IS more colorful than the MB display, so it might just get owners to pay attention a bit better. That's a good thing.

P.S. my RF tire always runs hotter. I was worried about a possible alignment problem, or brake dragging, but now I accept that it's because the I6 turbo is right there. Hot Corner!

 

I see, thanks for answering my curiosity.

 

Maybe in the beginning but then you'd probably you go back to checking the same amount of times as any other car. Just regression to the mean!