Tyre Pressure Sensor Accuracy

The first two, with the temperature at -2 C and the wind whistling is the Timmelsjoch between Austria and Italy. It was very cold, wet sleeting snow and bloody slippery.... and the café was shut. They actually closed the pass whilst I was up there, which I only discovered when I got back down on he other side.

The second two are the Stelvio, between Italy and Switzerland. Bright warm sunshine at the bottom, with snow on the top.

The bloke holding / supporting his right arm, is a friend of mine. He lost the use of the arm completely, when he was hit by another motorcycle, the rider of which lost control on a bend in the Dales. He now has the use only of his left arm, the right one merely hanging. He converts all his bikes himself (he was naturally right handed) to a left hand twistgrip, rerouting / changing the throttle cable, and re-routes what was once the front brake (operated by the lever) to be foot operated. As the foot is less sensitive than the hand, he removes one of the front discs and its associated brake assembly, or the bikes are over-braked. The clutch / gearchange stays as normal. I rode one of his bikes and it takes a bit of getting used to.

He rode his bike, with us, up the Stelvio and back down. The only problem he says, is that to counter steer right requires a pull on the left bar which generally opens the throttle! He can't push(or pull) on the right bar as his arm doesn't work at all. Try doing hairpins (as you'll find on the Stelvio) like that. The girl with the red highlights is his granddaughter, who rode pillion behind him on our tour of 10 days. His only oncession was to ask me to pillion her up and down the Stelvio, as he was unsure that at some point he wouldn't lose it on the hairpins, due to the problem explained above. He didn't and all was well. Bods on here moan about the Stelvio, I'd ask them to try it one armed and then return to moan.
 
Very impressed with your friend Wapping. Wow. I can't imagine doing any of that with one arm!

That sounds like an interesting ride down the other side...of a closed pass! It's when it gets like that, I'm really happy to be on the GS. I remember my old Pan European. Anything other than tarmac was a big stress! Though I did ride it in the snow a few times. Not to be repeated (I never dropped it tho).

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He does incredibly well. When he was hit in the Dales, his wife was on the back, his GS bike snapped in two by the impact. When the air ambulance turned up his wife kept on saying to the crew and God knows how many ambulance and police bods, “I need my handbag”. The crews were very sympathetic, assuring her they’d find it. But she kept on and on..... eventually she said, “You need to listen... I have had a heart and lung transplant. I call it my ‘handbag’ but it’s a proper medical bag. All my anti-rejection pills and Lord knows what else are in it, along with the contact details of my consultant etc”. This provoked a huge rush to find it, including policemen climbing over the drystone wall and hunting in a ditch to find it, fast.
 
He does incredibly well. When he was hit in the Dales, his wife was on the back, his GS bike snapped in two by the impact. When the air ambulance turned up his wife kept on saying to the crew and God knows how many ambulance and police bods, “I need my handbag”. The crews were very sympathetic, assuring her they’d find it. But she kept on and on..... eventually she said, “You need to listen... I have had a heart and lung transplant. I call it my ‘handbag’ but it’s a proper medical bag. All my anti-rejection pills and Lord knows what else are in it, along with the contact details of my consultant etc”. This provoked a huge rush to find it, including policemen climbing over the drystone wall and hunting in a ditch to find it, fast.
 
As the one who started this thread, I thought some of you might like an update...or not...

Having started to doubt the accuracy of my Venhill gauge I bought a new one and the readings between both are so close that it doesn't matter.

When the bike went in for its first service I mentioned the significant differential between pressure gauge readings and the TPMS. They check the system and agreed the TPMS was giving false readings of up to 0.3 bar (4.5psi in old money). They did a complete software update of the system and when I got home (only about 10 miles) the difference between my Venhill gauge and the TPMS was just 0.1 bar (1.5psi) front & rear. Close enough.

Went out for a ride yesterday and checked the tyre pressures just before I headed out. Front and rear readings using both gauges were were 2.5 bar and 2.9 bar. TPMS readings when I was 2 miles down the road were 2.8 front and 3.4 rear! Being in Aberdeenshire, the temperature was balmy for November at +5 to +9 degrees C which was very similar to when I picked up the bike following the service/software update.

So...it seems the TPMS has reverted back to its old ways. I feel another call to the Motorrad dealer will be on my list for tomorrow.
 
As the one who started this thread, I thought some of you might like an update...or not...

Having started to doubt the accuracy of my Venhill gauge I bought a new one and the readings between both are so close that it doesn't matter.

When the bike went in for its first service I mentioned the significant differential between pressure gauge readings and the TPMS. They check the system and agreed the TPMS was giving false readings of up to 0.3 bar (4.5psi in old money). They did a complete software update of the system and when I got home (only about 10 miles) the difference between my Venhill gauge and the TPMS was just 0.1 bar (1.5psi) front & rear. Close enough.

Went out for a ride yesterday and checked the tyre pressures just before I headed out. Front and rear readings using both gauges were were 2.5 bar and 2.9 bar. TPMS readings when I was 2 miles down the road were 2.8 front and 3.4 rear! Being in Aberdeenshire, the temperature was balmy for November at +5 to +9 degrees C which was very similar to when I picked up the bike following the service/software update.

So...it seems the TPMS has reverted back to its old ways. I feel another call to the Motorrad dealer will be on my list for tomorrow.

My friend, I suspect you are completely missing the point.

The air mass inside the tyre will remain unchanged as you ride. However, the temperature will vary continuously as the tire warms up due to riding as well as outside temperature. This means that the tire pressure will also vary accordingly.

The point with the temperature compensated TPMS is for the reading to show a almost constant value for what ever mass of air inside the tyre. That is the only way for the rider to be able to detect an air leak in the tyre. If the TPMS was not temperature compensated, the reading would vary with the tyre pressure. The rider would not know for sure if this was due to a temperature change inside the tyre or a leak.

Hence, the only time the tyre pressure read by the TPMS will match a calibrated pressure instrument would be for an tyre air temperature of 20 degrees.
It's all explained in the riders manual.

Your bike works as it is designed. If the pressure reading suddenly drops, there is an flat on it's way. Otherwise, no worries.
That type of monitoring is the sole purpose of the TPMS system.
 
As the one who started this thread, I thought some of you might like an update...or not...

Having started to doubt the accuracy of my Venhill gauge I bought a new one and the readings between both are so close that it doesn't matter.

When the bike went in for its first service I mentioned the significant differential between pressure gauge readings and the TPMS. They check the system and agreed the TPMS was giving false readings of up to 0.3 bar (4.5psi in old money). They did a complete software update of the system and when I got home (only about 10 miles) the difference between my Venhill gauge and the TPMS was just 0.1 bar (1.5psi) front & rear. Close enough.

Went out for a ride yesterday and checked the tyre pressures just before I headed out. Front and rear readings using both gauges were were 2.5 bar and 2.9 bar. TPMS readings when I was 2 miles down the road were 2.8 front and 3.4 rear! Being in Aberdeenshire, the temperature was balmy for November at +5 to +9 degrees C which was very similar to when I picked up the bike following the service/software update.

So...it seems the TPMS has reverted back to its old ways. I feel another call to the Motorrad dealer will be on my list for tomorrow.

Hi SimOv, As knutk says - your tpms is fine, you must stop focusing in on the pressure difference between your guage and the dash reading - these will not always match. Use and trust your calibrated guage on cold tyres and you're good to go.

From experience, the tpms comes into it's own when you puncture whilst riding as it will give you early warning of pressure loss.

David.
 
Hi SimOv, As knutk says - your tpms is fine, you must stop focusing in on the pressure difference between your guage and the dash reading - these will not always match. Use and trust your calibrated guage on cold tyres and you're good to go.

From experience, the tpms comes into it's own when you puncture whilst riding as it will give you early warning of pressure loss.

David.

Thanks knutk and David for words of guidance and reassurance. It isn't so much the fact that there is a pressure difference (I also have a K series and I'm familiar with those TPMS pressure differences), but it's more the scale of the difference...0.5bar (7.3psi). It was this 20% difference that prompted my dealer to rest the software at the first service, which did bring it back to a believable variation for a while. To show a rear tyre reading of 2.9bar (42psi) on the TPMS, my guages will read around 2.4bar (36psi).

So, I will continue to use my guages and senses to set the pressures, but I still wonder how many other GSA owners see this level of variation on their TPMS.

Thanks again.
 


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