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Old 03-01-2014, 09:30 PM   #15
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Originally Posted by beepaj View Post
So let me get this straight... If I were to have the Crossfires installed, does that mean I only need 1 tpms valve for each dual.
What the Crossfire system does is equalize the air in both dual tires by allowing you to add/release air in both of the tires from one valve. This is to insure that both dual tires maintain the same pressure.

A TPMS (Tire Pressure Monitoring System) system is electronic and sends a signal from each tire to a monitor in the cab of your vehicle. It requires a sender on each tire you want monitored and a receiver in the cab of your vehicle.


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Old 03-02-2014, 08:18 AM   #16
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I understand the concept of a TPMS system but I was wondering if the crossfire system equalizes the pressure in both tires couldn't the tpms sensor be attached to the crossfire thereby eliminating one sensor?
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Old 03-02-2014, 08:42 AM   #17
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Personally I do not recommend using the Cross-Fire System however it's totally up to each individual whether they do or don't.

There should be a one way check valve in the Cross-Fire which will prevent you from having TWO flat tires versus one.

How to use a TPMS system when using the Cross-Fire is a question that you should ask the company directly.

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Old 03-02-2014, 08:50 AM   #18
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Richard, you make an excellent point. Think I'll forget the Crossfire system.
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Old 03-02-2014, 09:19 AM   #19
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My coach on a Spartan chassis came with 3" solid metal extensions. I added the donut stabilizers after we had a cracked valve stem. I added Alligator caps to make pressure checks quick and easy. (Alligator caps have a double seal). That setup worked great until several years later I got a TPMS w/stem mounted sensors. I bought 4" solid metal extensions to get the sensors far enough out to use the donuts. The first 4" extensions I got from a truck tire place ...they were junk ...one missing a gasket and both had cores that were too short so I couldn't check pressures or add air. I then got 4" extensions from an RV dealer and they have worked great. And I do have the stems replaced when the tires are replaced.
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Old 03-02-2014, 10:00 AM   #20
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I understand the concept of a TPMS system but I was wondering if the crossfire system equalizes the pressure in both tires couldn't the tpms sensor be attached to the crossfire thereby eliminating one sensor?
Beepaj, I use a crossfire system and couldn't be happier with it. There are in fact check valves in the unit which prevent one tire or valve from causing both tires to go flat.

You can indeed use only 1tpms sensor for both tires but you will need to keep in mind that even if you have a flat it will only show a 10psi pressure reduction. If you prefer monitoring both tires you can use flow-thru sensors if they are available from your manufacturer. Of course if you had "in tire" tpms sensors you would have independent pressure measurements.

The Crossfire device had a few other interesting features other than visual pressure indication, as DrFilm suggested check out their website.

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Old 03-02-2014, 11:01 AM   #21
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Steve, thanks for clearing that up
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Old 03-02-2014, 11:02 AM   #22
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If your pressure gets down 50 psi,how do you know witch tire is leaking.You may be charged for flats
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Old 03-02-2014, 11:16 AM   #23
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http://yourtireshopsupply.com/catego...lly-valve-kits

Here is a link in case no one has provided it yet. My 22.5 duallys cost $130 when I put new tires on coach. Well worth it. I can sit for a month and not loose a pound of pressure. I check every time I get ready to move coach. No reaching or using extensions.
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Old 03-02-2014, 11:58 AM   #24
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If your pressure gets down 50 psi,how do you know witch tire is leaking.You may be charged for flats
Stan if you mean if one tire gets that low and you are using something like a Cross Fire system?

If that happened I would believe there would be several ways to check to see which tire was low, including visually.. you could also disconnect the crossfire and check each tire.
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Old 03-02-2014, 12:59 PM   #25
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Stan if you mean if one tire gets that low and you are using something like a Cross Fire system?

If that happened I would believe there would be several ways to check to see which tire was low, including visually.. you could also disconnect the crossfire and check each tire.

Not sure if I understand how the system works. Some say that it will let air flow from the higher pressure tire to the lower pressure tire so they both have the same pressure all the time.

So lets assume we start 80 psi cold. Drive down the highway and the temperature increases to 20F hotter than in the AM. The tire pressure goes up 4% so now both tires should have 83 psi. Now one picks up a nail so the air starts to leak out fairely quickly at about 10 psi an hour in that tire but the Cross fire lets air flow from the higher, non punctured, pressure tire flow to the one leaking.
Now we have two tires leaking at 5 psi an hour.
Some TPMS warn only when you are 15% below the cold setting so in this example that would be 68 psi. As air leaks out the tire will get hotter so the pressure increase due to temperature will partially offset the leak but eventually you would end up with two tires at 68 psi when the TPM sends a warning.

Not sure how you can tell which tire is leaking unless you disconnect the cross fire system, give the tires a couple hours to cool and for the punctured one to cool and leak more air. This may not be a bad thing as you will probably have to wait a couple of hours for the service truck to show up. By then you should be able to measure the pressure of the two tires and assume the lower one has the puncture.

After changing the punctured tire and re-inflating the non punctured tire, which has been slightly damaged from running 15% low.

Sounds like a plan. BUT this will only work if you have a TPM and cross fire system. If you only have the cross fire and get a slow leak in one tire but not slow enough to shut the valve you will destroy two tires.

The advantage of this set-up is there will be no question that you need to replace both tires because of a failure of one tire.

Not sure how a system can let air flow between two tires but never let air go from the high pressure tire to the low pressure tire except by limiting high flow rates.
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Old 03-02-2014, 08:40 PM   #26
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Your scenario is wrong. The crossfires close a valve once the tire pressure is 10 psi below design in either tire. So only one tire goes flat while the other tire stays at 10 psi below normal. A black flag is viewed through the window to let you know.
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Old 03-02-2014, 09:54 PM   #27
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If I was to purchase Dually Valve stems and go to tire shop for install what is an estimated cost on MH with 19" wheels? I'm talking about install using current tires. Is it also correct that TPMS will fit on the dually valve stems?

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Old 03-02-2014, 10:25 PM   #28
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Your scenario is wrong. The crossfires close a valve once the tire pressure is 10 psi below design in either tire. So only one tire goes flat while the other tire stays at 10 psi below normal. A black flag is viewed through the window to let you know.
Absolutely correct (as far as I know!)
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