Nordschleife

I rather thought I'd posted that twice I'd slowed from hight speed to 150, and had a tyre burst. I doubt I could have controlled it so easily had I been travelling at 200 mph or thereabouts.

The general rule we have developed is that if the pressure warning goes, we slow, go into 'tyre diagnostic mode' (does the car tend to pull in any particular direction, can you feel any vibrations, is there a thump or a noise, does it 'jiggle' evenly), if all seems clear we get back on the gas. we do however visually check the tyre and pressure levels at the next gas stop, which can happen as frequently as every 50 minutes.

Incidentally, at Le Mans, Audi have just changed the front bodywork on one of the cars because there was a problem with the TMPS antenna, and the drivers couldn't read the tyre pressure warnings, given that they are doing 220 plus mph (depending on aero package), they are quite attached to this feature.

R+C

Claudef2

Me uptight? I just spent 110000 US$, plus shipping and handling, on a car that gives me incorrect information. Sure, I can reset, recalibrate, adjust and fine tune. But why doesn't the TPMS give correct information in the first place? Compared to the wizardry going on inside the engine, reading 4 pressures cannot be that complicated. I don't have a pit crew at my house and all I want is a car that works. Get an iPod, you'll understand.

Nordschleife

Its you who doesn't understand - most of the time there is an apparent problem with TPMS, what has actually happened is that there has been a significant change in ambient air pressure or humidity.

The fact that you enumerate how much your car cost ($110, jeez you get cheap cars in the US - PAG must cut corners somewhere, perhaps they send all the defective TPMS over to the States) shows that you are getting uptight.

Get real, how often does the system require resetting? Once or twice a week, a month? If this gets tedious, fill the tyres with N, they will be more stable in pressure.

R+C

John Boggiano

Can anyone tell me briefly how to 'reset' the TPMS to a new baseline value?
As far as I can tell, mine will only accept the preprogrammed values for summer or winter tyres, I can't see a way to override it if I want to let air out on track...

Edit: I've been studying the documents from Beru in this thread (and RTFM), but am still confused until I do this 'hands on'.

1. If I run through the TPMS Set menu and tell it I just fitted a set of summer tyres, will the system then accept the pressures in the tyres at that moment as 'normal' (when adjusted to 20 degress)?

2. If so, does it then display those pressures as 29/33 psi (in other words, have I fooled into thinking they are at those values even if they're not), or at their actual values?

I'm starting to confuse myself...

Nordschleife

John

I'm not surprised you are confusing yourself! Much easier to try it out when the car comes.

Incidentally, I had a look at the BP site and discovered that there are quite a few places which allegedly sell 102 octane, but if you are attracted to Cape Wrath, its going to be tough to find. As my family are originally from Caithness, I understsand the problem.

R+C

NoSubEDU

Having TPS is nice for the occasional high-speed blowout and extra margin of safety, but it means nothing in track conditions.

In order for me to get the performance I want out of the car I have to drop the tire pressures down to about 32/35.5 HOT and that yields a cold tire temp that will certainly throw the sensors off when I start up the car- and remain so until I put air back into the tires for the ride home. I also recognize that the TPS is off by about a pound or two in the front and rear from time to time so it's not the most accurate measure.

However, I pay absolutely NO attention to the warnings when I'm on track. In fact I hardly know how fast I'm going because my attention is on the track and my vision as far as I can keep it.

The trick is knowing exactly how much pressure to put into the tire after the event and get rid of the warning. For me, 32/36 cold works. Gives me 29/33 on the TPS and that's the minimum before it throws the warning.

340Elise

R+C,

I am jealous that you get to enjoy the Autobahn on a regular basis. I noticed you are in Munich; that is where I was born. I did spend a couple of my driving years in Germany and enjoyed it immensely, except for the Stau of course.

You made a comment on the price of someone's US spec GT3 coming in at $110K. We really are lucky here with the prices and the warranties that we get. My father goes to Germany every year for 4 to 6 months and takes Euro delivery of a BMW every year; he uses it as his rental car, it ends up being cheaper than renting some 1.6 liter sewing machine hatch back. Anyway, this year he got the 335i and paid US $41K for it (including taxes, we have 3% in Albuquerque). I believe that is somewhere around $31 to $33K Euros. So he goes to the German BMW dealership and finds exactly his same car, except that in Germany every little thing is an option, including the steering wheel. Well anyway, the German version with the outrageous Mehrwertsteuer of 19%, plus the price of the car ended up being about $60K Euros. So basically, he got his for just about half the price of the German 335i. On top of that, I believe the German cars only have 1 or 2 years of warranty, while we get 4 years!

Of course I know the answer to why it is this way, but the point is, we are very lucky here in the US with the German cars and get them much cheaper. Most people (common people) think it is the other way around.

Anyway, I will be happy to get my GT3 at 107.5K, add a couple minor options and transportation and still come in under 110K US.

Enjoy Munich, it is a beautiful city; and maybe I will do a Euro delivery of my GT3 so I can enjoy it on the Autobahn and the Ring!

Stephen

Nordschleife

Stephen

Well now all of Europe gets a 2 year warranty, and most of us know how to legally recover the MwSt. On the plus side, I also get a two year warranty from the tuner, and it works, I've had new engines ands gearboxes without any problems. And it is nice to be personally known to the factory, which goes a small way to offset the cost.

Its much easier for me to get a car EXACTLY how I want it, and modified beyond the imagination of most people who find waiting a month or two for a car too long. One time I waited two years for a car, but the interim was filled with an assortment of really interesting loaners and 'rental' cars, driving experiences and trips, I don't suppose I ever would have thought to try an unfeasibly powerful VW Polo GTI (from VW Racing in Wolfsburg) otherwise, or been lent a GT2 with the suggestion I take it to the Ring!

You are right, Munich is a delightful city, my favourite in Germany, and a fantastic place to explore Mitteleuropa from. Presently I am overseeing some projects in ENgland and greatly miss Munich.

Interestingly, Pcars are amongst the cheaperst to own, if you take depreciation into account.

R+C

Racerron

Like so many things on the RS the TPMS is a total waste of time. Totally inaccurate, its off by as much as 4 p.s.i. I had mine disconnected . This was done by disconnecting the TPMS module and then preprogramming with the PWIS. The module MUST be disconnected !
I also removed the bulbs from the awesome footwell lighting package, next step is the suspension and am trying to figure out how to delete 300 pounds.

KINGSRULE

FYI


My TPMS's are off exactly 2 lbs. front and rear

John Boggiano

Edit: Anyone reading this post, please see the one two below this also.

OK, guys.

Reading through this thread, I can see there are some unanswered questions from quite a few people.

I'm sticking my neck out here, as I haven't put this to the test yet, I will try to do this tomorrow. But reading the posts on here and all of Beru's documents, I THINK the following is true - someone do tell me if you know it's not -

1. The TPMS doesn't actually display the current tire pressures as such, it simply assumes that at the last reset they were 29/33 and that is what it will show (extrapolated for temperature change) unless there has been air lost or added. This is subject to certain internal checks being made (it won't accept pressures at 'reset' if they are clearly way too low or if the front/rear differential is way too great).

2. Therefore, if your TPMS is 'inaccurate', you can recalibrate it by setting the pressures (note: with the tyres at 20 degrees) to 29/33 with an accurate gauge and then resetting the system (which will take ten minutes of driving). If your tyres aren't at 20 degrees, you need to make an allowance for the actual temperature - from memory, I think this is around 1.5psi per ten degrees.

3. If you wish to let air out, eg on track, you can either:
a. reset the sytem after doing so (which will fool it into thinking the pressures are OK [ie still at 29/33 when corrected for temperature] - within reasonable limits)
b. Simply ignore the warnings - which has the advantage that the 'info pressure' display will tell you how much you need to add at the end of the session in order to restore the pressures to their correct value when the tyres have reached 20 degrees again.
c. Carry a fifth transmitter, which will temporarily disable the system.
d. Have your dealer disable the system.

KINGSRULE

Not sure about #2

I have a Longacre digital tire gauge and when I recalibrate 29,33 it always reads 27,31.

Maybe the Longacre gauge is off....

John Boggiano

I've done some very thorough testing of all this TPMS stuff now, and the results show -

1. The system can NOT be calibrated by the user. A reset (with incorrect pressures in the tyres) will result not in a display of 29/33, but of the sytstem's interpretation of their true values.

2. The sytem doesn't rely on pressure gain or loss since the last reset to determine the current pressures to be displayed, it always measures and displays the 'true' pressure.

3. Thus, in my post a couple above this one, '1' is wrong, '2' is wrong, and '3a' is wrong.

Sad but true.

That leaves the possibilty that the dealer might be able to adjust the readout to agree with reality (if you feel yours is off) - might be worth investigating, but as mine only differs by 1 psi with most of my collection of gauges, I'm happy to leave well alone.