Planet-9 Porsche Forum banner
1 - 20 of 23 Posts

·
Registered
Joined
·
1,755 Posts
Discussion Starter · #1 ·
I was instructing and lapping with the Audi Club this Sunday. As I started my car to run in my session TPMS gives me a flat tire alert and shows rear left at -16...

WTF? Looks fine, I do not check pressures after each lap, as I set them based on tire wear. So everything was looking fine.

I plug the tire pressure gauge and yup... 23 PSI. Found a nice hex trim screw in the tire. Possibly from my own car or any other Audi / BMW that was running.

Anyway, without TPMS I would have come out not knowing. Made me reconsider not installing TPMS on my new track wheels. I will probably swap it in when I get a next set of tires.
 

·
Porscheholic
Joined
·
724 Posts
I think for 2006 TPMS was an option. So if I get the sensors installed would my system recognize it or the software probably needs to be updated?
 

·
Premium Member
Joined
·
2,803 Posts
I think for 2006 TPMS was an option. So if I get the sensors installed would my system recognize it or the software probably needs to be updated?
The sensors are the tip of the iceberg. For the Porsche TPMS you'll also need the wheel well receivers and TPMS wiring harnesses, as well as software changes.
 

·
Porscheholic
Joined
·
724 Posts
No No No. I wanna be a lazy Starbucks triple decaf soy hazelnut grande latte with just a squeeze of vanilla flavor type of yuppie. I do not have time to manually check my tire pressures every time I am using the car to transport me somewhere.:taunt:
 

·
Registered
Joined
·
1,755 Posts
Discussion Starter · #7 ·
Or you could just check tire pressures with a gauge before going on track
NEVER, EVER, have seen someone do that before EVERY lapping session. Yes, most people check it twice or three times per day. But I have never seen someone do it before EVERY session. Now, after this lesson while I do not have TPMS in my track wheels - I will be that person checking every time.
 

·
Registered
Joined
·
362 Posts
Interesting. I'm about to pull the TPMS sensors off of the wheels I'll be using at the track and install them on my (new) street wheels. Figure I'm pretty on top of the pressures at the track, so they are better used as an early warning system for street use. Plus -- they aren't very accurate and sometimes stop reading at the track (I assume due to heat -- they have always recovered later).

Tomasz makes a good point -- I'll be VERY diligent about checking pressures before every session from now on!

While on the subject, I have a question about the sensors: how does the car know which reading is from which wheel? The sensors or the wheel well receivers? Does it matter if I keep them on the same corners they are on now?

Cheers,
Walter
 

·
Premium Member
Joined
·
6,730 Posts
I do not check pressures after each lap, as I set them based on tire wear.
Tomasz, glad all went well and the TPMS worked for you. Can you please explain how do you set up the tire pressure based on wear?
 

·
Premium Member
Joined
·
2,803 Posts
While on the subject, I have a question about the sensors: how does the car know which reading is from which wheel? The sensors or the wheel well receivers? Does it matter if I keep them on the same corners they are on now?
The receiver in each wheel well identifies which wheel is at its position during the "learning" phase. You can move the wheels around as you wish.
 

·
Premium Member
Joined
·
3,495 Posts
NEVER, EVER, have seen someone do that before EVERY lapping session. Yes, most people check it twice or three times per day. But I have never seen someone do it before EVERY session. Now, after this lesson while I do not have TPMS in my track wheels - I will be that person checking every time.
I'm a tire checking maniac until I get them right. Then I check the as the weather changes....If it gets hot in the afternoon, I always have to drop a few psi out of them. NT-01s get very greasy if they run hot over about 40.

I try to have everything done before I get to the track. Hate to play mechanic and driver at the same time, but hot tire pressure has to be checked and corrected right away when you get off the track. On the first session or two, I'll come in and check after a couple laps and recheck until tires are staying where I want.

It would be pretty difficult for a leak to get too bad on my car. If a tire got to 20 PSI, I'd know something was up and would come in.

Generally, there are so many warning lights on my dash at the track, I probably wouldn't even notice TPMS. I have it but not for track wheels.

:drivingskid:
 

·
Tennessee Vol
Joined
·
649 Posts
NEVER, EVER, have seen someone do that before EVERY lapping session. Yes, most people check it twice or three times per day. But I have never seen someone do it before EVERY session. Now, after this lesson while I do not have TPMS in my track wheels - I will be that person checking every time.
I check it before every track session. It is required to bleed off the pressure. Otherwise the pressure will be too high very quickly into a 30 to 45 min session.
 

·
Registered
Joined
·
6 Posts
not to sound too preachy, but if you're not checking tire pressures after every session at the track, you're setting yourself (and maybe some of us too) for some huge problems.
you gotta check lugs and tire pressure every time. period.
 

·
Registered
Joined
·
202 Posts
Tomasz, glad all went well and the TPMS worked for you. Can you please explain how do you set up the tire pressure based on wear?
Tires have wear indicators on the sidewall. On Michelins, it is usually a little "Bibb" man embossed in the sidewall with his hand sticking up toward the tread like a pointer; it can be an arrowhead or arrow facing the tread; if you look, you can see them on all sporting tires.

If you come off the track and your worn, "melted" tire matter ends right at the top of your pointer/indicator, then you are wearing the tires right to the design "edge", meaning your driving technique and tire pressures are likely close to ideal for your tire. You are using all of the tread--you tire is not riding high on too much pressure, nor rolling over onto the sidewall with too little pressure.
 

·
Registered
Joined
·
202 Posts
not to sound too preachy, but if you're not checking tire pressures after every session at the track, you're setting yourself (and maybe some of us too) for some huge problems.
you gotta check lugs and tire pressure every time. period.
Good advice, and check your brake pad width, your rotors for cracks, your fluid levels, belts, and other easy visuals, too. Makes sense, no? With a Cayman, much is hidden so you cannot check, but check what you can.
 

·
Premium Member
Joined
·
6,730 Posts
Thank you Quick, but your explanation doesn't tell how to preset the tires before the track. If I understood you correctly, you are describing how would I know after the track or after seeing the wear on the tire if my preset was ideal.
 

·
Registered
Joined
·
202 Posts
Thank you Quick, but your explanation doesn't tell how to preset the tires before the track. If I understood you correctly, you are describing how would I know after the track or after seeing the wear on the tire if my preset was ideal.
You are right--the initial setting is a guess (although after you run a few events you should have a real good idea of your preferred starting pressures). You would have to ask others what their settings are and start there, then adjust as the day goes on. Driving style, venue, ambient temp, tire type, susp setttings, and other variables are in play.

I would seek out someone in your run group who runs the same tire and ask them. Ask several folks if possible and use an average to start. I usually start at about 30 f/r cold, as I want neutral handling. If I get over about 36 or 37 pounds or so right off the track, then I am going to release some pressure. After sitting for an hour or two, I will want the pressure around 31 f/r when I go out again. I will use the seat of the pants check on how the car feels and handles and look at the wear arrows, too. If you are running timed laps, you may find you can correlate your settings to your best lap times.


Keep records as you go so you can develop you own database of pressures that work for you. Observing the wear arrow indicator is but one indicia of correct tire pressure--some like more pressure in the front, or rear, to adjust for understeer or oversteer, some like to slide the car more than others, some like uneven pressure left to right if a track turns primarly right or left. You'll have to make your own determinations, as well as continue to consult with others.
 

·
Premium Member
Joined
·
6,730 Posts
Thank you very much Quick for this informative post... and God bless you for sharing your experience.

I truly appreciate it.
 

·
Registered
Joined
·
116 Posts
There are aftermarket tpms's available if you were so inclined. One of our good sponsors (rhymes with "fire hack") has them.

Check 'em out
Tire Rack : Tire Pressure Monitoring Systems
I have a similar aftermarket system on my Goldwing, and it works very well. I have found the readings to be extremely accurate, and I can monitor my pressure as I ride. I have the one where the sensors just screw onto the valve stem. Motorcycle tires loose about a 1/2lb of pressure each time you check the pressure, so I have had to add air much less frequently since I purchased the system (I realize this is not necessary applicable to car tires). YMMV.
 
1 - 20 of 23 Posts
Top