Deleted account 211025001
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Tyre Pressure Sensor Accuracy
- Thread starter SimOv
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Ok. You got me. I do exactly the same 
. I use a little compressor with a guage. I too measure in psi at that point 
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. I use a little compressor with a guage. I too measure in psi at that point 
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Ok. You got me. I do exactly the same
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It's spelt GAUGE
Now I took the comment, to be a negative hence I deleted the original reply.
(It was a long day, and i was shooting from the hip
Clearly the OP understood where i was coming from and came back with some meaningful data, which enabled an interesting and hopefully helpful discussion
(It was a long day, and i was shooting from the hip
Clearly the OP understood where i was coming from and came back with some meaningful data, which enabled an interesting and hopefully helpful discussion
Tall Lad
Registered user
Hi Simon,
I too found that the bike gives completely different reading to three separate pressure gauges all of which were within 1 PSI of each other. I rang the dealer and asked if they could re-calibrate but the answer was no. Told me that they have had lots of people ringing up about the same thing, he said use the bike's system as a warning if tyre gets low in pressure but use a pressure gauge to keep tyres to correct pressure.
I too found that the bike gives completely different reading to three separate pressure gauges all of which were within 1 PSI of each other. I rang the dealer and asked if they could re-calibrate but the answer was no. Told me that they have had lots of people ringing up about the same thing, he said use the bike's system as a warning if tyre gets low in pressure but use a pressure gauge to keep tyres to correct pressure.
Hi SimOv
The tyre presure sensor will not always show actual pressures, rather it shows compensated readings for an ambient temp of around 20 degrees C.
Here's a link to an old thread on ADV. https://advrider.com/f/threads/rdc-...s-actual-number-of-sensors-supported.1151421/
Enjoy your new bike!
M30SJM
Registered user
I also use a Venhill dial pressure guage before every ride, and my TPMS normally read 0.1 bar lower than the guage, and never alters from that all day, regardless of the ambient air or road temperature. If the dealer says they have a lot of people ringing about the same thin, I'd say there is probably an issue with the TPMS on the 1250's. I also dont agree with the line that you should just use them as an early warning of a flat, if this was the case why have it as a display option? you could just wait for the warning flat tyre symbol to come on the dash.
Stu
Stu
Can. Worms. Open.
Seriously, many thanks for all the input, suggestions and links. On page 165 (does anyone actually read this far?) of the owner's manual I have discovered it does explain some of the thinking behind the 20 degrees ambient temperature. However, the average temperature in Aberdeenshire is 13.5 degrees, so I may need to buy a new calculator.
The bike goes in for its first service next week so I'll take the opportunity to quiz the guys there about what still feels like a significant discrepancy, particularly if other 1250 owners are experiencing the same thing...and the TPMS variation on my K12 is minimal.
In the interim, I'll keep using the Venhill gauge.
Simon
Seriously, many thanks for all the input, suggestions and links. On page 165 (does anyone actually read this far?) of the owner's manual I have discovered it does explain some of the thinking behind the 20 degrees ambient temperature. However, the average temperature in Aberdeenshire is 13.5 degrees, so I may need to buy a new calculator.
The bike goes in for its first service next week so I'll take the opportunity to quiz the guys there about what still feels like a significant discrepancy, particularly if other 1250 owners are experiencing the same thing...and the TPMS variation on my K12 is minimal.
In the interim, I'll keep using the Venhill gauge.
Simon
Hi SimOv
The tyre presure sensor will not always show actual pressures, rather it shows compensated readings for an ambient temp of around 20 degrees C.
Here's a link to an old thread on ADV. https://advrider.com/f/threads/rdc-...s-actual-number-of-sensors-supported.1151421/
Enjoy your new bike!
That is my experience
In the summer (?) months the TPMs on my 1250 GSA were very close to my tyre gauge. More recently as the air temperature has dropped the TPMs have a wider discrepancy with my trusted gauge. The reasons for this can be found in my 2019 model Rider's Manual on page 165. It also explains how you can get an accurate reading on the bike's screen but this involves a LOT of faffing around!
On another bike I own I have a (relatively) cheap Chinese TPMs...........the one with a sensor in the valve caps. This registers the actual pressure in the tyre and when I set off it is very close to my gauge. As the tyre warms up so the pressure increases. On a hot day this can be over 5psi in the rear tyre but I know this and can compensate accordingly
I find this far better than the over complicated BMW system. I get an accurate reading when I first set off and will be warned of any swift deflation
Mike
I read that far into the manual - actually, I read the whole thing. But I never quite grasped how and in what way it would 'adjust/compensate' for temp changes. Of course, I understand now, but that came from using it!
On my first trip to Italy in June this year, it was v warm the whole ride. But when I went over the pass (2600m) there was still a lot of snow and it was bloody freezing. So from 26-28° down at the bottom to about 9° at the top of the pass. As I set off after taking some shots and sending some messages - about 15min, I quickly noticed something not right with the handling (I'm a bit sensitive - some say I worry too much
). I checked the tyre pressures on the dash and sure enough, it showed them to be down by about 1-1.5 bar. Yes, as I descended and the temps rose, so did the displayed pressures.Presumably there is a standard/predicable rate of pressure change depending on temp that the system uses to adjust/compensate.
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You're right. I'm doing a half mental conversion and messing it up.
The rear I run at an indicated 3.0 bar. That's what it read the whole trip. Up on top of the pass, it reduced to an indicated 2.7 bar, which was noticeable to the ride - lots of luggage and lots of twisties so easy to feel the change.
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Thant makes sense. In that situation, now you know about it, before going up I'd add 0.2 bar (3psi) to compensate. I'd rather have it high than low with weight on board. Then when you get down again, it's easy to let some back out. Under normal load, 3psi wouldn't make a great deal of difference over a short time, the tyre would be warmer than the ambient temperature anyway.
Yes. Putting a little more in would be easy too as I have a compressor and guage (
).Coming back a week ago there was a far less pronounced affect as all temps were closer (8° at the bottom, -1° at the tunnel (pass was closed)).
But getting back in course to the OP's point. My pressure gauge and tpms match quite well. Unlike his, which seemed quite off.
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In all my time of going to the alps, I don’t think I’ve ever once seen anyone fiddling with their tyre pressures before ascending to the top of a pass, irrespective of the expected temperatures at the top, nor fiddling with them again on their return at the bottom.
To be honest, I probably wouldn't be arsed to change them. But it's the first time I had that experience. Now I know, I'll just be ready for it next time. I tend to have quite a bit of luggage, which will probably increases the chances of feeling any change in pressure.In all my time of going to the alps, I don’t think I’ve ever once seen anyone fiddling with their tyre pressures before ascending to the top of a pass, irrespective of the expected temperatures at the top, nor fiddling with them again on their return at the bottom.
ps. Where are your shots from? Great shot down into the valley.
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