# Dual Tyre Pressure Equalisation System



## wildebus (Sep 11, 2018)

I like Tyre Monitoring Systems and bought a 6-wheel system for my LT Dually.  I had problems with it as the extra weight of the sensors on the Valve extenders tended to cause the elbow extender to loosen and so loose pressure. The extender actually has loosened a couple of times without the sensors so was a hassle.

I searched around the internet for options and came across the Crossfire system and really liked the sound of the features.
This is the manufacturers web page on the problem - Crossfire - Dual Dynamics

You need to choose a kit that matches the Pressure you want to run at - they are no adjustable.  When I first looked at these I was not sure what pressure I would be running the rear tyres at as didn't know my final running weight.  Once I had near enough completed the conversion, loaded up with the most I planed to carry (which is quite a bit in the garage sometimes), took to the weighbridge and from that weight, further research and a handy and timely tyre pressure thread on this forum, decided 65PSI would be the pressure of choice for my rig.

So looked for a 65PSI Crossfire kit and as luck would have it found a nearly-new pair of 65PSI units on Ebay.com (US Site).  The units with postage and import duties came to around £60 which is very good.

Installation was a bit trickier then the instructions and youtube videos would have you believe though (at least on my vehicle).  In order to properly secure the hose on the inner wheel I had the remove the outer wheel to allow room for the 13mm spanner to tighten the hose nut. The sequence of fitting like this means you lose pressure while the Crossfire is partly disassembled (but not a big problem and actually means you get to check its operation as part of the install  )
Overall, including jacking up the van each side, removing a pair of wheels, installing the kit and refitting wheels, retorquing, dropping jack and packing away took maybe 60 minutes.

Once Installed this is what it looks like on a LT/Sprinter Dual Wheel


Crossfire Installation by David, on Flickr

When at the pre-set Pressure, the display is Yellow and there are two black marks that line up with the marks on the surround


Crossfire Installation by David, on Flickr

This shows the Yellow section coming into view as I am inflating the tyres up to pressure


Crossfire Installation by David, on Flickr

When the pressure is 10PSI below the pre-set, the display is black.  This shows mostly black as I am at around 55PSI


Crossfire Installation by David, on Flickr

Not tried this feature yet, but if the pressure is 10PSI OVER the preset the display shows red.  This is quite possible to happen due to the way tyres warm up and it is more of a informational display rather then a problem one.


What I really like about this system is not just it tells you at a glance the pressure is at the setting you want when you do your walkround before driving off, but it keeps the tyre pressures matched between inner and outer tyres, plus it gives you just one fill valve for both tyres which is dead handy I think.
(to pre-answer one common question on this system, the unit is monitoring both tyres and if one tyre suffers rapid deflation, the valve shuts off.  For a slow leak, the valves shut off when the pressure drops 10PSI below the preset (so 55PSI for me))

One thing which I am wondering a little about is if the extra off-set weight on the wheel will introduce any vibration?  I suspect however it won't be noticable.

I might fit the TPMS sensors from the unit I already have to the central valves as I do have the system anyway and so could use the 2nd set of rear sensors on my little trailer.


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## wildebus (Sep 11, 2018)

Have a read of the info on the website I linked to learn why.

There will be a reason why a company has developed this kind of equipment and put a lot more research and knowledge into it than I have.  So I am inclined to believe the benefits (especially as on two occasions I have had one tyre at way lower pressure than the other due to loose extenders and that was not good - and you cannot tell on a dually if there is this discrepancy (I certainly didn't notice until I got out the van and saw the tyre didn't look right each time)


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## Byronic (Sep 11, 2018)

I don't suppose you'll be able to sense imbalance on the rear, but you'd definitely
need a rebalance if a gauge such as that needs to be fitted to the front.
As the pipe goes through the rim cutouts it could abrade on the metal edge
with wheel movement, but the lines look like s/s braided so probably OK long
term.


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## wildebus (Sep 11, 2018)

Byronic said:


> I don't suppose you'll be able to sense imbalance on the rear, but you'd definitely
> need a rebalance if a gauge such as that needs to be fitted to the front.
> As the pipe goes through the rim cutouts it could abrade on the metal edge
> with wheel movement, but the lines look like s/s braided so probably OK long
> term.


The kits come with apieces of rubber hose (looks like fuel pipe to me) that goes over the hose for the inner wheels to address that rubbing and potential abrasion  
The elbow for the outer wheel is touching the wheel and I might put a bit of rubber on that to isolate it though.

The kit looks a bit old fashioned and judging from the intro video, has been around for a while, but I think it is one of those "if it ain't broke, don't fix it" type of products and feels VERY robust and high quality  (hope so anyway!)


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## trevskoda (Sep 12, 2018)

Ok if no leak over from one tyre to other,vibes may be a prob at high speed but most dont go to fast im sure.
I would prefair in cab monitor to be honest.


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## wildebus (Sep 12, 2018)

trevskoda said:


> Ok if no leak over from one tyre to other,vibes may be a prob at high speed but most dont go to fast im sure.
> I would prefair in cab monitor to be honest.


Trev, did you read the info on the website? It links the two tyres to equalise them dynamically so you could say there is a "leak" from one to other but in the way that is good.
I will probably fit the TMPS to the central valve as well.  I could add some balance weights opposite the gauge possibly for some approximate balance .


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## wildebus (Sep 12, 2018)

Thought this kit came out a while ago .... Read a posting on a sprinter forum yesterday from someone who said he had been running a crossfire system for 20 years! (A post 5 years earlier said 15 years so it sounds like he has had just the one kit so bodes well for product longevity).


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## phillybarbour (Sep 12, 2018)

That’s a fancy bit of kit


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## trevskoda (Sep 12, 2018)

wildebus said:


> Trev, did you read the info on the website? It links the two tyres to equalise them dynamically so you could say there is a "leak" from one to other but in the way that is good.
> I will probably fit the TMPS to the central valve as well.  I could add some balance weights opposite the gauge possibly for some approximate balance .



If one got a hole then would both not go down.:scared:


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## wildebus (Sep 12, 2018)

trevskoda said:


> If one got a hole then would both not go down.:scared:


Nope! That is a key feature of it. Equalises between the two tyres upto 10psi below preset PSI and below that the valves are shut off so one tyre cannot impact the other past that level, but the display tells you there is low pressure.
My limited experience of dual tyres has already taught me that visually it is not obvious one of the pair is low, especially if it is the inner tyre so this kind of info is good to have. Plus being able to put air into dually tyres as easily as into a standard single tyre is ace


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## trevskoda (Sep 12, 2018)

wildebus said:


> Nope! That is a key feature of it. Equalises between the two tyres upto 10psi below preset PSI and below that the valves are shut off so one tyre cannot impact the other past that level, but the display tells you there is low pressure.
> My limited experience of dual tyres has already taught me that visually it is not obvious one of the pair is low, especially if it is the inner tyre so this kind of info is good to have. Plus being able to put air into dually tyres as easily as into a standard single tyre is ace



Cheers thats handy though i have valve extenders on my rear units which i find handy but i like they tyre pall sys with monitor in cab,expensive mind you.


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## wildebus (Sep 12, 2018)

I had the Tyre Pal system on a previous van and liked it.
When I got the LT, I bought this 6-tyre system - CARCHET RV Trailer Car Solar TPMS Tire Pressure Monitoring System +6 Sensors LCD Display: Amazon.co.uk: Car & Motorbike - plus some valve extenders (you helped point me in the direction of them).
But I found the extra weight of the sensors made the extenders move around and wasn't comfortable with that.
I didn't seem to be able to tighten them down to lock in place. That seems to be quite a common thing as I have seen these inserts that are shaped to fix in one of the wheel holes with a centre for the extender to go through so it cannot move around.

Just done a search ... This kind of thing (which I don't have) - Valve Stem Stabilizers - RealWheels


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## Byronic (Sep 12, 2018)

trevskoda said:


> Cheers thats handy though i have valve extenders on my rear units which i find handy but i like they tyre pall sys with monitor in cab,expensive mind you.



Just go half way Trev. and fit those tyre valve cap monitors, a few quid just have
to be prepared to get off your butt once in a while and look. That's the trouble with 
young people, everything has to be on a display screen and inside !

I don't know if they're available in >60-70psi though.


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## witzend (Sep 13, 2018)

Just some other gimack to go wrong don,t see any on twin wheel lorrys. Just a hit with hammer will tell if pressure down after a bit of practice you,ll soon know if ones low


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## wildebus (Sep 13, 2018)

witzend said:


> Just some other gimack to go wrong don,t see any on twin wheel lorrys. Just a hit with hammer will tell if pressure down after a bit of practice you,ll soon know if ones low


excellent advice   do you lick the dipstick to check if the oil needs changing as well?

PS.  could you tell me where to calibrate my hammer?


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## witzend (Sep 13, 2018)

wildebus said:


> excellent advice   do you lick the dipstick to check if the oil needs changing as well?
> 
> PS.  could you tell me where to calibrate my hammer?


If your silly enough to make such a reply theres no point trying to educate you


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## wildebus (Sep 13, 2018)

witzend said:


> If your silly enough to make such a reply theres no point trying to educate you



:lol-049::lol-049:
Pot .... Kettle .... :dog:


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## trevskoda (Sep 13, 2018)

wildebus said:


> I had the Tyre Pal system on a previous van and liked it.
> When I got the LT, I bought this 6-tyre system - CARCHET RV Trailer Car Solar TPMS Tire Pressure Monitoring System +6 Sensors LCD Display: Amazon.co.uk: Car & Motorbike - plus some valve extenders (you helped point me in the direction of them).
> But I found the extra weight of the sensors made the extenders move around and wasn't comfortable with that.
> I didn't seem to be able to tighten them down to lock in place. That seems to be quite a common thing as I have seen these inserts that are shaped to fix in one of the wheel holes with a centre for the extender to go through so it cannot move around.
> ...



Mine have clips which have a pinch bolt to fasten to rim,the clip has a u section where the valve neck locks in,trucks all use them.


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## trevskoda (Sep 13, 2018)

Byronic said:


> Just go half way Trev. and fit those tyre valve cap monitors, a few quid just have
> to be prepared to get off your butt once in a while and look. That's the trouble with
> young people, everything has to be on a display screen and inside !
> 
> I don't know if they're available in >60-70psi though.



I do a walk round before each trip but if your running double back wheels and get a flat on inner one the dash monitor is sure to be the safe option for quick stop and change before the tread flys of with overheating.:scared:


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## GWAYGWAY (Sep 13, 2018)

I have a feeling the blokes would run out the rear door when you in for a Tyre balancing session.


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## trevskoda (Sep 13, 2018)

Here is what i use.


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## Byronic (Sep 13, 2018)

trevskoda said:


> I do a walk round before each trip but if your running double back wheels and get a flat on inner one the dash monitor is sure to be the safe option for quick stop and change before the tread flys of with overheating.:scared:



That happened to me somewhere between Malaga and Calais a few years back.
Not frightening. Because I didn't notice a thing whilst running! Only when stopped in Calais 
chanced to look under van, shredded inner. But most of the tread in one piece attached to 
sidewalls in short strips.


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## trevskoda (Sep 13, 2018)

Byronic said:


> That happened to me somewhere between Malaga and Calais a few years back.
> Not frightening. Because I didn't notice a thing whilst running! Only when stopped in Calais
> chanced to look under van, shredded inner. But most of the tread in one piece attached to
> sidewalls in short strips.



Driving behind a truck one day i could smell burning so past him and waved him in,when stopped the inner rear ps tyre was melting and almost on fire,thanked me and radioed in for tyre truck to sort him out,prob missed the ferry at larne to scotland.


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## Byronic (Sep 13, 2018)

GWAYGWAY said:


> I have a feeling the blokes would run out the rear door when you in for a Tyre balancing session.



Kind of already has a balance weight fitted just a question of hitting it with 
a hammer to position correctly :lol-061:


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## wildebus (Sep 13, 2018)

Byronic said:


> Kind of already has a balance weight fitted just a question of hitting it with
> a hammer to position correctly :lol-061:


As long as the hammer is calibrated correctly .....


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## Byronic (Sep 13, 2018)

wildebus said:


> As long as the hammer is calibrated correctly .....



24oz. plus or minus 20oz. close enough calibration for a Quikfit Fitter!


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## Kennyd (Sep 14, 2018)

*£5 fix*

I like Tyre Monitoring Systems and bought a 6-wheel system for my LT Dually. I had problems with it as the extra weight of the sensors on the Valve extenders tended to cause the elbow extender to loosen and so loose pressure. The extender actually has loosened a couple of times without the sensors so was a hassle.


Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 


I would put threadlock on the elbow extenders , problem solved 

If you need to take them off again , they will free with a little heat 




Loctite 2700 OEM Specified High Strength Thread Lock & Sealant- Stud/ Nutlock 8713899012857 | eBay


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## trevskoda (Sep 14, 2018)

Kennyd said:


> I like Tyre Monitoring Systems and bought a 6-wheel system for my LT Dually. I had problems with it as the extra weight of the sensors on the Valve extenders tended to cause the elbow extender to loosen and so loose pressure. The extender actually has loosened a couple of times without the sensors so was a hassle.
> 
> 
> Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> ...


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## GWAYGWAY (Sep 14, 2018)

trevskoda said:


> Here is what i use.



I had a set of those on the Twin wheel transit   BUT the  inner one got out of its  bent clip and just reached the road where it ground off the valve end leaving me with a flat , in the middle of nowhere in the dark, luckily it had not  messed up the tyre.  I managed to remove it and blow up the  tyre using the proper valve but  it was awkward to get that, it was the reason I bought the extenders in the first place.   Only trouble I ever had with that van was the tyre valves, they were factory fitted ones and the were mostly rubber as the brass did not go down as much as proper valves  do.. Turkish supplied rubbish, four went before I bit the bullet and bought  metal valves to replace all six.. The rubber had perished and gave slow punctures through side crack on the body of the valve.. Ford knew but never said.  Turkish factory, built chassis.


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## Byronic (Sep 14, 2018)

I install Transit TR-600 rubber and brass rated max. 100psi. 
Schrader marked (who really knows these days?) Made in Chinaland. Never
a problem.
Plastic extenders for the inner rears, simple as can be, in
keeping with the rest of the van mechanicals. More joints
equals more chance of leaks in my lexicon of understanding.



Lexicon....so much better than book


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## wildebus (Sep 17, 2018)

Not driven the Camperbus since fitted this kit until today.  Checked the displays and still spot on as I left them so no leaks there 
Couldn't detect any induced imbalance due to the extra gauges and hoses when driving. 
Checked the gauges when I got home after final 15 mile drive and they were both like this:



Gauge after driving by David, on Flickr
Very much as expected and described by the maker  - over pressure due to the heat induced when driving.  Being half yellow, half red I would estimate 70 PSI (as 10 PSI down changes from full yellow to full black and I'm guessing the change is linier).

I'll refit the TPMS sensors on the van now I have checked the gauges are good so I can dynamically monitor all the tyres (plus the trailer when I tow that)


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## wildebus (Sep 26, 2018)

Bit of a delay with the TPMS as when I installed it most of the sensors didn't seem to work   checked the batteries and all but one was under 3V (uses 3V batteries).
So bought a pack of batteries from Amazon and reinstalled the sensors this evening.

Looks nice and neat on the Crossfire unit as well



TPMS on Crossfire by David, on Flickr

Now the TPMS system I got was a 6-wheel setup designed for either Vehicle + Trailer or a 6-wheel vehicle  (the display actually represents a Dually). I bought this before I was aware of the Crossfire system and wanted to monitor all the wheels.
With this system I had two extra sensors now as the Crossfire combines each pair of wheels and presents a single valve (as shown above).  So what to do with the spare sensors?

I was going to fit them to my trailer, but I don't use the trailer much, plus it doesn't seem possible to set the second set of rear sensors differently to the first set, so the pressures would not be right.
I noticed that the TPMS kit has an option for a Spare Wheel sensor :idea-007:  So this is what I did!  Recoded one of the spare sensors to become the Spare Wheel sensor, and left the last sensor without a battery and as a general spare.

So 4 main wheels show in the display



TPMS Display by David, on Flickr

The spare alternates between the primary and secondary sensors.  This is the one showing the spare



TPMS - Spare by David, on Flickr
I need to recode the last sensor to remove it from the default 2nd dually wheel so that wheel doesn't show anymore, but only takes a few minutes to do.

It is quite a neat TPMS system.  I like the fact it uses a little solar panel to keep it charged so not tied to being wired up for power.


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