[NKOTB2015]

Okay...I think I finally got the issue resolved and it was something unexpected, so I figured I'll share in case someone experiences same/similar issue.

It turns out that I have a slow leak in front passenger tire (must be very slow since I don't daily the car and it never went low enough to trigger the TPMS alert.) I probably wouldn't have noticed if it wasn't for the leftoverture recommendation on the tire psi, so thank you sir!

FYI, the front passenger side tire psi dropped to 26psi (driver side front @34psi and both rears @36psi). Once I got the slow leak fixed and now that I'm able to maintain 34psi in both fronts, no more issues. Surprised how sensitive this car is to tire psi...

[zoro2001]

Thanks for the update.
I'm surprised that an 8psi difference didn't trigger the TPMS.

[leftoverture]

Originally Posted by NKOTB2015

Okay...I think I finally got the issue resolved and it was something unexpected, so I figured I'll share in case someone experiences same/similar issue.

It turns out that I have a slow leak in front passenger tire (must be very slow since I don't daily the car and it never went low enough to trigger the TPMS alert.) I probably wouldn't have noticed if it wasn't for the leftoverture recommendation on the tire psi, so thank you sir!

FYI, the front passenger side tire psi dropped to 26psi (driver side front @34psi and both rears @36psi). Once I got the slow leak fixed and now that I'm able to maintain 34psi in both fronts, no more issues. Surprised how sensitive this car is to tire psi...

Glad it worked out for you.

[Ajowhan]

Originally Posted by zoro2001

Thanks for the update.
I'm surprised that an 8psi difference didn't trigger the TPMS.

I think it goes on a +-5/6 or something like that, maybe his was set to 30/31 so it would only goes off on 25. And he is reading 34 when warm

[zoro2001]

Originally Posted by Ajowhan

I think it goes on a +-5/6 or something like that, maybe his was set to 30/31 so it would only goes off on 25. And he is reading 34 when warm

Could be. I wouldn't check one tire cold, then go for a ride, then check a different tire warm. I would just check all the tires at the same time........but that's just me.

[Nickies]

Originally Posted by NKOTB2015

Okay...I think I finally got the issue resolved and it was something unexpected, so I figured I'll share in case someone experiences same/similar issue.

It turns out that I have a slow leak in front passenger tire (must be very slow since I don't daily the car and it never went low enough to trigger the TPMS alert.) I probably wouldn't have noticed if it wasn't for the leftoverture recommendation on the tire psi, so thank you sir!

FYI, the front passenger side tire psi dropped to 26psi (driver side front @34psi and both rears @36psi). Once I got the slow leak fixed and now that I'm able to maintain 34psi in both fronts, no more issues. Surprised how sensitive this car is to tire psi...

IDrive is accurate to monitor tire pressure. A so much drop would have been noticeable if you drive for at least 10 miles on a freeway.

Yes..... the car is very sensitive to even a drop of 2lbs on either tires for front or rear axles and even more if you have a staggered set-up.

This becomes an issue for RWD if they are outbalanced on hard acceleration because in same time you will strongly feel loosing traction and this is not feeling good.

I would say the 240i always need 4 even tires. You must always replace them as a set of 4 otherwise the car behaving is unpredictable. Just my opinion.

[freakystyly]

Originally Posted by Nickies

I would say the 240i always need 4 even tires. You must always replace them as a set of 4 otherwise the car behaving is unpredictable. Just my opinion.

I've noticed the rears wear almost twice as fast as the fronts. If square setup like my winter set, just need to rotate.

My staggered summer PS4s rears seem to have excellent lateral grip well past the wear bars. But noticed the straight line grip isn't what it used to be.

[Nickies]

Originally Posted by freakystyly

I've noticed the rears wear almost twice as fast as the fronts. If square setup like my winter set, just need to rotate.

My staggered summer PS4s rears seem to have excellent lateral grip well past the wear bars. But noticed the straight line grip isn't what it used to be.

If you want better life on a staggered PS4s set, my experience is you have to rotate cross axle every 4K.

It works well for me and the tread wear is even on all 4. I keep them at 38F/45R.

If you loose straight line grip on acceleration, your tires need to be replaced.

[AmuroRay]

PSI too high in the rear. You likely have non Runflats at runflat PSI

[Kernel Kurtz]

Originally Posted by AmuroRay

PSI too high in the rear. You likely have non Runflats at runflat PSI

What is runflat PSI? Pretty sure most passenger car tires operate in the same range...

[AmuroRay]

Originally Posted by Kernel Kurtz

What is runflat PSI? Pretty sure most passenger car tires operate in the same range...

Well. Reading the thread, I was wrong. Op said he had run flats
But on the door, I thought it was pretty high depending on tire size. So maybe up yo 40psi?

Either way, it's higher than a normal tire, and higher pressures cause the tire to elongate and reduce the contact patch. Happened to me.

I have 18x9 in my rear with 255/35?/18s and keep it at 34ish

[Kernel Kurtz]

Originally Posted by AmuroRay

Well. Reading the thread, I was wrong. Op said he had run flats
But on the door, I thought it was pretty high depending on tire size. So maybe up yo 40psi?

Either way, it's higher than a normal tire, and higher pressures cause the tire to elongate and reduce the contact patch. Happened to me.

Yeah, the door stickers are for a fully loaded car, whether run flat or not. And yeah, over 40 is crazy in either case unless you are approaching the max load rating of that tire. Most people seem to find mid 30s to be ideal for performance. I run 35 all around on my RFTs. When people say they run the 45 it says on the door sticker that is just what we call a whatever. If you don't know any different by all means carry on.

[AmuroRay]

Originally Posted by Kernel Kurtz

Yeah, the door stickers are for a fully loaded car, whether run flat or not. And yeah, over 40 is crazy in either case unless you are approaching the max load rating of that tire. Most people seem to find mid 30s to be ideal for performance. I run 35 all around on my RFTs. When people say they run the 45 it says on the door sticker that is just what we call a whatever. If you don't know any different by all means carry on.

What's on the door isn't the maximum pressure, it's the recommended based on spec. I went to a dealer who decided to air up my tires and they were bumping it up to 38psi, which made the rear feel unstable.
I put it down to 34 and all is well.

[Kernel Kurtz]

Originally Posted by AmuroRay

What's on the door isn't the maximum pressure, it's the recommended based on spec.

It is based on max GVWR, which is also on the door. I'm sure I've posted this link here before, but it is still a good refresher for those who have not read it before.

https://www.motortrend.com/features/...ssure-sticker/

[NKOTB2015]

To me, what I was happy to find was that the front PS tire was low, thus explains why the symptom felt more pronounced in left sweeping curves (there by loading up the front PS tire more). I was wrecking my brain checking and comparing left and right side components...lol

[AmuroRay]

Originally Posted by Kernel Kurtz

It is based on max GVWR, which is also on the door. I'm sure I've posted this link here before, but it is still a good refresher for those who have not read it before.

https://www.motortrend.com/features/...ssure-sticker/

I read the link, and it literally does not say that.

[Kernel Kurtz]

Originally Posted by AmuroRay

I read the link, and it literally does not say that.

What it literally says is "Every car comes with an NHTSA-mandated tire pressure label, usually found inside the driver's door, that lists a set of tire pressures as well as the maximum combined load for passengers and cargo. NHTSA will simply tell you to run those max-load cold tire pressures".

[AmuroRay]

Originally Posted by Kernel Kurtz

What it literally says is "Every car comes with an NHTSA-mandated tire pressure label, usually found inside the driver's door, that lists a set of tire pressures as well as the maximum combined load for passengers and cargo. NHTSA will simply tell you to run those max-load cold tire pressures".

Again, I read it. It does NOT say that the (Maximum) tire pressures are based on vehicle load. The label itself is mandated, what it says can vary by manufacturer

"Some car companies list multiple recommended inflation pressure combinations based upon the load the vehicle is carrying, speed, tire size, and what type of tire is fitted—winter, summer, etc."

[Kernel Kurtz]

Originally Posted by AmuroRay

Again, I read it. It does NOT say that the (Maximum) tire pressures are based on vehicle load. The label itself is mandated, what it says can vary by manufacturer

"Some car companies list multiple recommended inflation pressure combinations based upon the load the vehicle is carrying, speed, tire size, and what type of tire is fitted—winter, summer, etc."

So I'm curious then, how do you think the pressure numbers on your door sticker were chosen?

[Bud miller]

maybe weather temperature cold day and cold tires will make a big diff
since weather change from a mo ago

[Nickies]

Originally Posted by Kernel Kurtz

So I'm curious then, how do you think the pressure numbers on your door sticker were chosen?

Good question .......... I may have a part of the answer but just guessing.

Why the OEM PSS summer tires were branded BMW? Where they made of a different compound of the Michelin regular tires that we get on the aftermarket? This may explain why they were labeled to run at very high pressure like mine at 38/45.

[Kernel Kurtz]

Originally Posted by Nickies

Good question .......... I may have a part of the answer but just guessing.

Look in your owners manual. It will list a bunch of different pressures. Note which particular combination is on the door....