TPMS sensors

My SR3 has TPMS and I have used it one day at the track, and then not again.  They are great on my public roads cars and even trailers, but I feel they are less than useless on the track because:

- setup is cumbersome

- they can lose pressure easily because the rubber seals are not nearly as good and durable as a basic rubber valve stem.

- they have whole number precision whereas my pressure gauge measures to 1/10 psi 

- when you swap wheels/tires, you would need another set of four tpms sensors

- it makes removing and mounting tires a little bit more difficult

- the sensors tell you the tire pressure, but you still need to use a gauge to bleed off air to level the tire pressures at the track

Even if I run myself, I can get out of my car at the end of the session to take tire pressures.  At a race or test event, most drivers have a technician in pit lane with a pressure guage.

There is some benefit however, and that would be to see how the pressure changes during a driving session, and you would also see the max and minimum pressures, which I believe is available in the Aim data log.  In my opinion they are unnecessary and not worth the trouble.  I would be interested to hear other opinions and any success stories.

Very much agree with David on the TPMS sensors... We've had two demo cars with these fitted and only ever used it to "confirm" they are working...

The only benefit I could see to these is if you are working with data to check evolution of temperature (and pressures) during longer runs and while preparing for a race, but even then the temperature you get is a generic indicator of the overall tyre temp and not as precise as measuring inside, centre and outside across the tyre surface.

Interesting discussion with good points.  I've always wanted TPMS, but never added it.  My reasons were: 1) understanding tire pressure progression over a session via data analysis 2) understand tire temp during a session both cold/early conditions and overheating conditions that may call for a cool down lap and 3) peace of mind if I can't recall whether I set the pressures after I left the pit

Certainly, I can see the inconvenience added wrt tire changes and I never considered the issue of air leaks.

The type that Aim sells is a poor design and prone to air leaks in my experience.

I have used this type on the track, truck, and on my trailer, and I have lost the air seal on all which should never happen with a valve stem.  I had a slow leak on one truck tire, and after replacing the rubber seal on the tpms sensor, it fixed the problem.  I don't know whether some wheels are better than others for this type of valve stem design, or if it boils down to torqing the nut sufficiently.  My preference is to eliminate this potential failure point.

I found a different type which is more like the basic valve stem, and it holds air well on my trailer tires.

There is no nut to tighten on this type -- it gets seated with a valve stem puller tool just like a basic valve stem.  Eventually I will swap out the metal type with this type on my truck.

I think IMSA rules requires the use of TPMS, which would mean that the race teams have figured out how to use it safely.

I use the TPMS kit from TrailBrake.com. No leaks, 3 sets of sensors. I've incorporated the pressure and temp data into my AiM configurations, and send it via CAN to the ECUMaster PMU and MoTeC ECU. My crew (aka my wife, lol) and I set initial tire pressures using a manual gauge in the mornings, then monitor/record it during the day. I can't say I've gotten much use out of the pressure data (but there's always hope!), and setting pressures requires a manual gauge (one can't monitor the dash and adjust tire pressures simultaneously). 

One thing I will say though: tire carcass temps are useful. Hankook says the tires work best at 80-100*C. I can only get tires up to about 80* even on my best laps on hot days which tells me I am still leaving lap time on the track.