Tyre Pressure Sensor Accuracy

SimOv

SimOv

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Hi all.
Having picked up our new 1250 GS Adventure TE about 3 weeks ago I am loving every mile I can put under the wheels.
All is rosy as they say, but I have noticed a large (well, I think it is large) inaccuracy with the tyre pressure sensor readings. I have a Venhill pressure gauge that was check for accuracy about four months ago and it under-reads by about 0.1bar, so 2.9bar will show as 2.8bar on the dial. I also have two other gauges that are reasonable accurate, but not checked.
On the new GS, what I know to be a correct 2.9bar when the rear tyre is cold, shows up as 3.3bar on the bike. The front shows 2.9bar on the display when I know is is 2.5bar.
I've been rinding for long enough to be able to make a call on what feels right on the bike and adjust pressures accordingly, but is this level of inaccuracy of the GS pressure monitors normal?
I would add that I also have a K1200 R Sport and the bike pressure gauges typically over-read by about 0.1-0.2 bar max.
Grateful for your thoughts.
Many thanks, Simon
 
Personally I wouldn't worry about it at all, instead use the system if you do ever start to lose air as an indicator you need to do something quickly..

I certainly set my pressures to my gauge every time in bikes and cars.
 
Fuck it.

Im getting the popcorn in, and lets see how far it can run
 
Thanks Santa. Interesting reply and thoughts on the subject, and those dark nights haven't really reached you yet. I assume I'm not getting a present this year?
The accuracy of the Venhill gauge was verified by one of my closest friends who is a qualified UKAS assessor and measures and calibrates scientific instruments down to...well...lots of decimal points. On that basis, I'll take his error measurement reading of 0.1 bar to be close enough for me. That's my theory.:cool:
 
SimOv said:
Thanks Santa. Interesting reply and thoughts on the subject, and those dark nights haven't really reached you yet. I assume I'm not getting a present this year?
The accuracy of the Venhill gauge was verified by one of my closest friends who is a qualified UKAS assessor and measures and calibrates scientific instruments down to...well...lots of decimal points. On that basis, I'll take his error measurement reading of 0.1 bar to be close enough for me. That's my theory.:cool:
Click to expand...

Wow we have a decent start point :), you may be back on the nice list ;)

What was the temperature when you took the reading was it cold, or after a ride?

0.1 bar is 1.45psi i dont have my handbook to hand so i cant remember what the upper an lower limits are

But i'm guessing your gauge only reads in 1 or 2 psi increments or is it digital ?, so you could be 2psi out an normal reading either from the gauge or the sensor

personally i wouldn't worry. i looked at my readings couldn't be arsed to do the calculation from bar to Psi and never go near that screen now ;)
 
SimOv said:
Thanks Santa. Interesting reply and thoughts on the subject, and those dark nights haven't really reached you yet. I assume I'm not getting a present this year?
The accuracy of the Venhill gauge was verified by one of my closest friends who is a qualified UKAS assessor and measures and calibrates scientific instruments down to...well...lots of decimal points. On that basis, I'll take his error measurement reading of 0.1 bar to be close enough for me. That's my theory.:cool:
Click to expand...
I have a Venhill guage that I believe to be accurate. I also have a month old GSA TE. The guage and TPM read the same when the tyres are cold. The TPM compensates for increasing temperature, so they probably would not read the same when the tyres are warm!
I'd get back to the dealer; see if they can alter/check the calibration.

Sent from my SM-A520F using Tapatalk
 
Check tyres regularly with an accurate gauge ( your Venhill)
Use the TPM as an indicator for pressure loss: the actual numbers don’t matter IMO.
 
Hurrah! Maybe I will get a present after all!:thumb
Pressure difference was on cold tyres...within 300-400 metres of pulling away. Interestingly, the measurements on the monitor didn't change regardless of time spent on the road or how hard they were worked. The gauge is a dial with 1.0psi/0.1bar increments and you can see it here...
https://www.venhill.co.uk/news/VT32RiDE/
As mentioned, I'm happy to go with the gauge but I'm curious about the experience of others.



Santa-2512 said:
Wow we have a decent start point :), you may be back on the nice list ;)

What was the temperature when you took the reading was it cold, or after a ride?

0.1 bar is 1.45psi i dont have my handbook to hand so i cant remember what the upper an lower limits are

But i'm guessing your gauge only reads in 1 or 2 psi increments or is it digital ?, so you could be 2psi out an normal reading either from the gauge or the sensor

personally i wouldn't worry. i looked at my readings couldn't be arsed to do the calculation from bar to Psi and never go near that screen now ;)
Click to expand...
 
stanley said:
I have a Venhill guage that I believe to be accurate. I also have a month old GSA TE. The guage and TPM read the same when the tyres are cold. The TPM compensates for increasing temperature, so they probably would not read the same when the tyres are warm!
I'd get back to the dealer; see if they can alter/check the calibration.

Sent from my SM-A520F using Tapatalk
Click to expand...


Thanks Stanley
Yes, that was my thinking.
 
Yep, should be spot on. Remember to report back and let us know how you get on

Sent from my SM-A520F using Tapatalk
 
The TPM on the bike is calibrated to read the correct pressure at 20 deg c ambient air temp, so if you check them at a higher or lower temp with a gauge, the TPM display will read different to your gauge. The bikes handbook tries to explain this, but it is not that clear to understand and it does not really explain why it is like this.
 
I'm on an an old fashioned 1200 TC, which has TPMS. Never had it before so it took me a while to get my head around just what it was doing.

I think the comments above ref getting the pressures right on your Venhill guage then using the bikes system as a warning for lots of pressure is the things to do - which sounds like what you're doing actually . But a bit annoying not to have the bikes system matching your guage a bit closer.

This summer, which was a good one, I did some fairly big miles in hot temps. I check my tyres with a separate guage, like you. My TPMS says 2.7bar and 3.0bar (front/rear) and that's my cold pressure starting point. After a good 11hrs in the saddle, in hot conditions, it reads the same....! So clearly it's compensating.

But your main issue with the discrepancy. Sounds big to me. I'd see if the dealer can re-calibrate it.

Sent from my SM-G975F using Tapatalk
 
GSMarky said:
Personally I wouldn't worry about it at all, instead use the system if you do ever start to lose air as an indicator you need to do something quickly..

I certainly set my pressures to my gauge every time in bikes and cars.
Click to expand...

Rowle said:
Nice reply to a new member .......
Click to expand...

What was wrong with the reply, seriously :nenau

I wouldn't use TPMS readings as an absolute but they are there as a handy monitor if I start losing air due to a slow puncture or whatever........so for me accuracy is irrelevant.

Also, am I the only one that won't use Bar but still uses psi? There's too much difference between tenths of a Bar AFAIC and I much prefer working with a finer (larger?) scale which psi gives me.

Andres
 
Outtomunch said:
What was wrong with the reply, seriously :nenau

I wouldn't use TPMS readings as an absolute but they are there as a handy monitor if I start losing air due to a slow puncture or whatever........so for me accuracy is irrelevant.

Also, am I the only one that won't use Bar but still uses psi? There's too much difference between tenths of a Bar AFAIC and I much prefer working with a finer (larger?) scale which psi gives me.

Andres
Click to expand...
I thought the reply was fine too!

But with psi, surely there are too many increments compared to bar? I mean, there's more opportunity for the sensor readings to 'appear' to fluctuate a lot more?

Sent from my SM-G975F using Tapatalk
 
Ajay said:
Check tyres regularly with an accurate gauge ( your Venhill)
Use the TPM as an indicator for pressure loss: the actual numbers don’t matter IMO.
Click to expand...

Agree, the TPM is best considered as an indicator of a tyre deflating so that you can safely stop in good time or as an indicator of a slow puncture/valve leakage. Use a manual gauge on cold tyres before you ride.
 
Slipperyeel said:
I thought the reply was fine too!

But with psi, surely there are too many increments compared to bar? I mean, there's more opportunity for the sensor readings to 'appear' to fluctuate a lot more?

Sent from my SM-G975F using Tapatalk
Click to expand...

Ah yes agreed, I meant when setting pressures using a gauge. I find it a lot easier to set to, say, 42 psi than I do 2.9 Bar.

Andres
 
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