[Boothmeister]

Hi there all.

I've just come back to the BMW world with a 2015 F30 330D. I've only had the car a week but last night the warning light came on for one of the wire pressures being low. All of them were low to be honest but one was a lot lower, lol.
So today I pumped all of them up to 38psi as per the chart in the drivers door and then reset them on the iDrive. The tires were all cold at the time and by the time the system had measured all of the pressures the rears were at 36psi and the fronts at 37psi. I went back home, parked up and then got back in the car some 90mins later and the same rear that was really low had already dropped to 33psi. I've checked around the tire and find nothing to indicate a puncture (not guaranteed I know) but whilst on the drive to work which is 13miles on A roads the pressure had gone back up to 36psi.
So I guess my question is - does that sound like a puncture or a faulty sensor? I know tire pressure increases as they warm up but not of the other pressures moved, or barely moved anyway.
I have warranty and insurance against the a puncture but rather than mess about I wanted to get a feel for which is going to be more likely given the pressure fluctuations.

Thanks for ready, Chris.

[rak299]

sounds like a puncture to me. Tire pressure gauges are famous for being inaccurate. I assume plus or minus 5% - 10%. I would first examine the tread all the way around for a nail.

[Boothmeister]

Yeah. Think I'm gonna get the wheel off tomorrow and put some water on in to see what I can see.

[wurstrocket]

So I just wanna say ive been having a very very similar issue for weeks since I bought my CPO 435i

Ive taken it back to BMW 4 times now. At first all tires were losing pressure slowly. I checked with a gauge to make sure the sensors were not faulty. it matched.

I took the car to BMW and they said they reseated the tires because of beading.

I picked up the car and the front right tire started losing pressure.

Took it back to bmw. They said there was too much beading.

Picked it up and 3 days later the back left tire was losing pressure.

Apparently they said they reseated every tire but this one and the SA didnt know why.

Picked up car and 1 week later back left tire was leaking again.

At no time was a puncture ever detected but the paperwork kept showing leaks around the edges of the wheels.

I talked to the manager and they kept my car for 2 weeks. At this point its been in the shop roughly 80% of the time ive owned it for tire leaks. I told the manager i was basically paying to drive a loaner car at this point.

They took the car and reseated every tire and rebeaded everything again. Thats where im at. We will see if it last. But I flipped out last time and if it happens again im gonna lose it.

Im looking at buying new rims and tires but I need what I have to hold up until I can sell these and make them someone elses problem. My thoughts are this 1 tire that leaks frequently is bad and they just dont want to replace it. Because BMW service sucks.

I would be surprised if its anything but a bad tire. These things happen.

[rphz]

Originally Posted by wurstrocket

So I just wanna say ive been having a very very similar issue for weeks since I bought my CPO 435i

Ive taken it back to BMW 4 times now. At first all tires were losing pressure slowly. I checked with a gauge to make sure the sensors were not faulty. it matched.

I took the car to BMW and they said they reseated the tires because of beading.

I picked up the car and the front right tire started losing pressure.

Took it back to bmw. They said there was too much beading.

Picked it up and 3 days later the back left tire was losing pressure.

Apparently they said they reseated every tire but this one and the SA didnt know why.

Picked up car and 1 week later back left tire was leaking again.

At no time was a puncture ever detected but the paperwork kept showing leaks around the edges of the wheels.

I talked to the manager and they kept my car for 2 weeks. At this point its been in the shop roughly 80% of the time ive owned it for tire leaks. I told the manager i was basically paying to drive a loaner car at this point.

They took the car and reseated every tire and rebeaded everything again. Thats where im at. We will see if it last. But I flipped out last time and if it happens again im gonna lose it.

Im looking at buying new rims and tires but I need what I have to hold up until I can sell these and make them someone elses problem. My thoughts are this 1 tire that leaks frequently is bad and they just dont want to replace it. Because BMW service sucks.

I would be surprised if its anything but a bad tire. These things happen.

If I were you I'd go back and demand a new set of tires if you have any more issues. What tires/sizes are they?

[paimon.soror]

double check around the tpms sensor too (soapy water). They are notorious for leaking as the rubber gasket wears. Tire shops are supposed to replace them every time they mount a tire. I've had 2 that needed a rebuild on my 2016 due to leaking issues.

[ReallyRadams]

Originally Posted by rak299

sounds like a puncture to me. Tire pressure gauges are famous for being inaccurate. I assume plus or minus 5% - 10%. I would first examine the tread all the way around for a nail.

How come they are inaccurate?
My car said the psi is 32 (correct psi) but my $10 digital gauge says 34. Both readings are cold.