TimC
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| posted on 13/2/20 at 08:51 PM |
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Anyone using a Tyre Pressure Monitoring System for trackday?
I tend to be a one-man band. Anyone using one of these?
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peter030371
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| posted on 13/2/20 at 09:41 PM |
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What type/model are you thinking of? To really be of any use you would need a decent (expensive) one.
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gremlin1234
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| posted on 13/2/20 at 09:47 PM |
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as above, there are at least 2 ways of measuring, and one using 'abs ring sensors' would be very unlikely to work well on circuit
racing.
reason being: they count the tyre revolutions and compare to the other tyres.
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MikeR
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| posted on 13/2/20 at 11:54 PM |
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most TPMS systems use 433mhz transmission. You can read the output on a 20 quid usb tv reciever. If the manufacture transmission has been decoded you
can get tyre pressure and temperature.
(look up rtl_433 - open source software).
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peter030371
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| posted on 14/2/20 at 08:40 AM |
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A little more detail to my previous answer 
Anyone that knows me will say I am not one for blowing my own trumpet. Along with my team of staff I have designed, developed and manufactured TPMS
systems for over 20 years now and for the last 18+ years all for a leading tyre manufacture for one of the harshest uses in the world (it makes F1
look like a breeze)
I tend to be aware of most reasonable systems on the market, always keeping an eye on the competitors 
To get any sort of useful pressure information you will need to spend at least £500 IMHO (probably twice that) and this being a locost forum I suspect
that is over your budget? The lower cost systems just will not give accurate (or repeatable) enough information for track work.
The valve screw on types can cause air leaks as the thread form on the outside of a schrader valve is often very poor (low cost), it is designed to
keep a valve cap on not keep air in!
If you think you have found a system that will work for you let me know and I will tell you what I know about that system 
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steve m
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| posted on 14/2/20 at 09:23 AM |
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Sorry to hijack this thread, but Pete may know the answer to my question
Pete, why are some TPMS systems so bad, I work for an Insurance/car rental company, and doing so drive brand new cars
all the time, the worst brands for TPMS faults/errors are BMW and Honda, both of which have to go back to the main stealers to be rectified, just
wondered if they use the same system ? as I can not recall any other brand of vehicle that has had any faults
And we have pretty well everything from Nissan Jokes to Bentley's
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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peter030371
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| posted on 14/2/20 at 09:51 AM |
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quote:
Originally posted by steve m
Sorry to hijack this thread, but Pete may know the answer to my question
Pete, why are some TPMS systems so bad, I work for an Insurance/car rental company, and doing so drive brand new cars
all the time, the worst brands for TPMS faults/errors are BMW and Honda, both of which have to go back to the main stealers to be rectified, just
wondered if they use the same system ? as I can not recall any other brand of vehicle that has had any faults
And we have pretty well everything from Nissan Jokes to Bentley's
steve
I think they both use schrader sensors (as do many others) but they will each have there own custom implementation. The devil is in the detail and
maybe some implementations are better than others or maybe they are just set to be more sensitive.
My Discovery has never warned me of low pressures and yet I have seen them drop from the set pressure of 32psi to <25psi and the car said
'all is fine'...so at what point do they warn me!
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TimC
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| posted on 14/2/20 at 11:28 AM |
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quote:
Originally posted by peter030371
A little more detail to my previous answer
Anyone that knows me will say I am not one for blowing my own trumpet. Along with my team of staff I have designed, developed and manufactured TPMS
systems for over 20 years now and for the last 18+ years all for a leading tyre manufacture for one of the harshest uses in the world (it makes F1
look like a breeze)
I tend to be aware of most reasonable systems on the market, always keeping an eye on the competitors
To get any sort of useful pressure information you will need to spend at least £500 IMHO (probably twice that) and this being a locost forum I suspect
that is over your budget? The lower cost systems just will not give accurate (or repeatable) enough information for track work.
The valve screw on types can cause air leaks as the thread form on the outside of a schrader valve is often very poor (low cost), it is designed to
keep a valve cap on not keep air in!
If you think you have found a system that will work for you let me know and I will tell you what I know about that system
What a great answer - I’d probably have spent £100 but not £500 or £1000.
Thank you - I’ll keep leaping from the car to check.
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coyoteboy
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| posted on 14/2/20 at 01:29 PM |
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What's the limiting factor Peter? Seems like MEMS pressure sensors are likely to be pretty fragile for in-wheel mounting. I'm curious
about the technical problems (purely from an academic standpoint)!
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peter030371
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| posted on 14/2/20 at 04:59 PM |
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quote:
Originally posted by coyoteboy
What's the limiting factor Peter? Seems like MEMS pressure sensors are likely to be pretty fragile for in-wheel mounting. I'm curious
about the technical problems (purely from an academic standpoint)!
The MEMS sensors from the likes of Schrader, Infineon, Freescale, Melexis etc are all quite robust. They all use a very similar silicon stack
principle for the actual measurement, I think Sensonor really pioneered this in the 90's. I have xrayed, micro-sectioned and examined quite a
few now 
The problem is generally very limited power, so limited readings and/or transmissions or you get a flat battery.
Not many batteries can work at the upper temperatures you see in a tyre. Even on the road >90C is possible on a step alpine decent (heat soak from
the brakes) for short periods and most cells will fail at this temperature. For road use some manufactures are now demanding a sensor life of 10 years
i.e. for the life of the car without the battery going flat. We don't work in units as large as milli or micro amps but down to nano and now
pushing pico amps on ceramic boards with silver and/or palladium conductors.
Some TPMS sensors only have a dozen or so electronic parts in them but everyone is very carefully chosen after lots of testing and qualifying at
extreme temperatures (-40 to +125) and various pressures.
We then supply them all over the world for fitting in these
 
big tyre
You could buy a Caterham 620R with the cost of just one of these tyres and still have enough change for a new Ford Fiesta (and each truck has 6 tyres)
Does that help your academic thirst 
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JMW
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| posted on 14/2/20 at 08:06 PM |
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quote:
Originally posted by peter030371
..............
If you think you have found a system that will work for you let me know and I will tell you what I know about that system
What can you tell me about the Carchet TPMS model CQ575 please?
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peter030371
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| posted on 14/2/20 at 09:53 PM |
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quote:
Originally posted by JMW
What can you tell me about the Carchet TPMS model CQ575 please?
Old Chinese model, doubt it's accurate. By a decent gauge with the money
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fregis
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| posted on 15/2/20 at 08:00 AM |
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If use two sensors on wheel maybe will have more accurate reading (on wheels who have two stems)?
p.s. just kiding
Never be afraid to do what you are insolvent, remember: amateurs built the ark - Professionals built the Titanic.
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peter030371
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| posted on 15/2/20 at 08:57 AM |
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quote:
Originally posted by fregis
If use two sensors on wheel maybe will have more accurate reading (on wheels who have two stems)?
p.s. just kiding
It has been tried for critical applications but if you get two different readings which do you believe?
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MikeR
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| posted on 15/2/20 at 10:06 AM |
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What level of information accuracy are you looking for? My neighbours Toyota sensors report pretty consistent results. If you got some tpms valves
fitted, then took readings to calibrate what it reported against your normal pressure guage - would that be close enough?
(I'm assuming you can fit the sensors to any shell when you change the tyres.
NB. Consistent means I got the same pressure within 1/2psi every day - I guess in reality the pressure for be changing but the sensor isn't
reporting it
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peter030371
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| posted on 15/2/20 at 01:55 PM |
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quote:
Originally posted by MikeR
What level of information accuracy are you looking for? My neighbours Toyota sensors report pretty consistent results. If you got some tpms valves
fitted, then took readings to calibrate what it reported against your normal pressure guage - would that be close enough?
(I'm assuming you can fit the sensors to any shell when you change the tyres.
NB. Consistent means I got the same pressure within 1/2psi every day - I guess in reality the pressure for be changing but the sensor isn't
reporting it
In my Striker 20psi feels horrible but 18psi feels so much better. although I couldn't tell you which is faster 20 just feels very harsh. So I
would say 1/2psi is not really good enough. Gut feeling is to be really useful you need 0.1 or 0.2 psi accuracy for a 7 type car on track.
These DIY guys that are using standard TPMS sensors with a basic RF grabber and decoding the information are not measuring the atmospheric pressure at
the same time so they end up with absolute pressure not gauge pressure. They could just deduct 14.7psi to get a rough idea but they could be almost
1/2psi out depending on the air pressure that day.
Then we get onto the temperature of the air in your tyre (not the temperature of the tyre) .... Boyle's law rules here
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fregis
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| posted on 15/2/20 at 03:36 PM |
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quote:
Originally posted by peter030371
quote:
Originally posted by fregis
If use two sensors on wheel maybe will have more accurate reading (on wheels who have two stems)?
p.s. just kiding
It has been tried for critical applications but if you get two different readings which do you believe?
none, will find sensors which shows similar results. Still good or bad reading hard to tell, but if they show similar, it posible reading good, so
then you can put sensors to diferent wheels
Never be afraid to do what you are insolvent, remember: amateurs built the ark - Professionals built the Titanic.
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jeffw
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| posted on 16/2/20 at 07:48 AM |
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Having had cars with TPMS and cars without I'd go without. My wife's Honda Civic Tourer has warned about TPMS pressures on and off since
new, nothing the Honda garage does seems to fix it.
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peter030371
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| posted on 16/2/20 at 08:40 AM |
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quote:
Originally posted by jeffw
Having had cars with TPMS and cars without I'd go without. My wife's Honda Civic Tourer has warned about TPMS pressures on and off since
new, nothing the Honda garage does seems to fix it.
Do you want to borrow my big hammer? It seems to fix lots of problems for me
Unfortunately most cars need an trained electronic engineer to fix them the days, being able to use an OBD reader means nothing 
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MikeR
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| posted on 16/2/20 at 08:50 AM |
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I'd the sensors are producing a reading, then I'd be willing them to replace the sensors which I imagine they're reluctant to do.
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