[AP]

thought Id pass this on as a tip for those of you who have TPWS on your car.

TPWS is the system that uses the ABS sensors to detect if there is a difference in speeds of a wheel compared with others to work out if you have a puncture.

A few weeks back I got a warning that the rear right tyre was low in pressure. I popped into a garage to pump up the tyre and inspect it and the machine for soem reason would not appear to want to pump up the tyre. It could pump up the others but just not this one. I thought perhaps teh valve was faulty in someway. I tried at afew more garages and got the same result.
I reinialized the TPWS system each time.
The tyre looked ok so I carried on as usual.

This weekend I put around 400 miles on the car, mostly fast and motorway miles. I noticed that over road markings and bad parts of the road, the car did not feel right and the rear end felt loose. ON teh motorway itself, it felt fine. There were no warnings displayed by the check control system.

When I got home I decided to have a closer look.
The tyre although at first glance appeared ok, was very slightly different in its profile and compared to the others , the sidewall was ever so lightly more compressed. In isoliation, it looked fine though. It was however warm to teh touch.....

I drove to another garage and had the same result with the air machine in that it refused to pump it up.
I drove to another garage and had teh same result, I then noticed that there was a setting on teh machine for flat tyres. I pressed this and hey presto , the tyre now started to accept air. It however showed that there was only 11PSI in it.
No wonder it didn't feel right.
So with it back to normal, the car felt back to its normal self.
I had put the bad handling down to tramlining and bad roads and was kidding myself that the roads were that bad, but this was rfeally just a symptom of the low tyre.

So lessons learned :-

Firstly if I was busying a car again today, I would specify TPMS and not TPWS.

When you reinitialize the car after pumping up tyres, it would apprear that the system is comparing the wheels against this reference. It is not capable of detecting a low tyre pressure as you have told what the norm is (which is not right).

So make sure that all tyres are equal and then reinitialize.
Don't initilialize if tehre an issue with a tyre or it will mask a genuine problem.

Check the tyres regularly.


Although the tyre visually looks ok, I'm going to replace it as it may fail at some point and the inside may be in a mess , which I cannot see.

I am however impressed with how far and how long you can drive on these tyres when they are deflated. I was driving up to 70mph on them and have covered at least 400 miles which seem way in excess of what the manufacturers state. (I think generally 50 miles and <50mph)

It also shows that visually checking a tyre is not easy, and I could only tell by comparing to the other tyres.

I though I'd pass this on as it may be of benefit to people. If it helps

[HighlandPete]

Also we need to remember that TPWS is not telling us if all four tyres are going down. Many have been caught out with low pressures in all wheels. It is a limited system and no substitute for still regularly checking our pressures with a gauge.

I agree on you replacing the tyre, you have probably used up the 'run-on-flat' capacity over those miles.

HighlandPete

[Gilgorm]

What you call TPWS is called FTM (Flat Tire Monitor) in my car and manual.
From personal experience with a completely flat tire (3.5 inch tapcon screw) the FTM only works when the tire is either completely or virtually flat. I filled it normally to 40 pounds and reset the FTM to drive to the garage one last time. The FTM only popped on when the tire was again completely flat.
The sidewall was NOT showing any problem initially but was bowing out after only about 50km.

The tire had to be replaced.
I prefer TPMS to the FTM system since small changes are communicated to the driver vs a complete flat. BMW cheaps out with the cheaper FTM in many markets.

[AP]

as I'd say, if i'D have better, I'd have ordered TPMS.
Checking tyre pressure is a still part and parcel of standard car maintanence , TPWS is really just a bonus on top of that to notify you of a completly flat tyre as it's not necessairly obvious.

As mentioned before, very impressed with the mileage that was got out of the tyres (Michellin Primacy by the way). Although they look fine, they are on borrowed time and need replacing to be on the safe side.
So thats going to make my wallet around £400 lighter this weekend.
275/35 19" don't come cheap, it annoying as I had this very tyre replaced some months back due to a nail in it........

[The X Men]

Hmmm, the tire would not pump up and there is a tire pressure warning on your dash and you try to blame the TPWS ????

[AP]

I'm not blaming the TPWS but wanted to highlight its limitations.
any additional info is always a help if youre speccing up your F10 now.
i'm to blame for the checks .
One of the reasons of these forums is to pass on infomation and experiences, and thats whats I'm doing.

I would certianly suggest any speccing a new car to opt for TPMS.

[The X Men]

Originally Posted by AP

I'm not blaming the TPWS but wanted to highlight its limitations.
any additional info is always a help if youre speccing up your F10 now.
i'm to blame for the checks .
One of the reasons of these forums is to pass on infomation and experiences, and thats whats I'm doing.

I would certianly suggest any speccing a new car to opt for TPMS.

In the US, the direct TPMS doesn't show the psi of each tire in the idrive, so it still would not have help you in your case. As a pilot once told me, trust your instruments unless you can prove it is wrong.

[remmib]

Didn't know it was called TPWS, what does it stand for?

BTW, I'm selling my 19" Michelin Primacy RFT in the Autumn, 1000 miles on them (getting winters on the 351M wheels).

[AP]

TPWS Tyre pressure warnign system - based upon ABS seonsors
TPMS Tyre pressure monitoring system. Based upon sensors in the wheel measuring pressure and temperature.

I'd assume that TPMS would pick up on low pressures on tyres. It might not display the actual pressure on idrive unless you'#ve coded that (google that).

[The X Men]

Originally Posted by AP

I'd assume that TPMS would pick up on low pressures on tyres. It might not display the actual pressure on idrive unless you'#ve coded that (google that).

The same would have happen in a TPMS if you re-initialize the system while one tire is low on air. I have had a few cars that have in-direct TPWS and they work pretty good considering the method. The one possible difference might be that some TPMS have a hard coded low pressure alarm, meaning you cannot initialize the system if a certain tire is under a certain psi, not sure if BMW have that.

[MalithS]

Originally Posted by AP

as I'd say, if i'D have better, I'd have ordered TPMS.
Checking tyre pressure is a still part and parcel of standard car maintanence , TPWS is really just a bonus on top of that to notify you of a completly flat tyre as it's not necessairly obvious.

As mentioned before, very impressed with the mileage that was got out of the tyres (Michellin Primacy by the way). Although they look fine, they are on borrowed time and need replacing to be on the safe side.
So thats going to make my wallet around £400 lighter this weekend.
275/35 19" don't come cheap, it annoying as I had this very tyre replaced some months back due to a nail in it........

I'd suggest you look at event tyres. Got a pair of the same tyres on my car from them and they were 320 each and Michellin also had a £50 voucher offer on at the time for 2 or more tyres.

[rhinosaur]

Originally Posted by AP

TPWS Tyre pressure warnign system - based upon ABS seonsors
TPMS Tyre pressure monitoring system. Based upon sensors in the wheel measuring pressure and temperature.

I'd assume that TPMS would pick up on low pressures on tyres. It might not display the actual pressure on idrive unless you'#ve coded that (google that).

My F11 is MY2013 and I got TPMS in it. In iDrive you can see the actual pressure and temperature of each tire, and according to the manual you get a warning if/when pressure is off by 25% or more.
I never had any problem so far. I check pressure regularly and find this system to be quite accurate (to the decimal of bar) in comparison with the gauges at gas stations. I even configured one of the 8 softkeys to jump directly to the TPMS screen on one click!

By the way, your story shows one of the advantages of run-on-flat tires over conventional ones!

[AP]

cool it sounds like your car has the settings for the actual temps and pressures that many have had to resort to coding ffor on earlier models

yes tyres are impressive and it would appear that the < 50mph < 50mile limitation is conservative, at least with the Michellin Primacy that I have.

[AP]

well I had the tyre replaced this morning and asked if I could see the old tyre afterwards to see how bad it was. There was a nail in the middle of the tyre but the interesting thing was that externally the tyre looked fine.
inside there was some powder where rubber had flaked off where the tyre was running deflated.
The dealership were quite surprised at how far and how fast the car had been working on a tyre that had been deflated. I dare say it could have lasted longer but it was on borrowed time and the only safe thing to do was replace it.
It's worth bearing in mind how good these tyres are in the event of a puncture.