Now you can have Crossfire AND TPMS

[Bob Cochran]

As a tire engineer I have trouble understanding the meaningful benefit of having the two tires match exactly for pressure given that tires will heat-up in use which increases the pressure (load capacity) until there is equalibrium.

 

If you only use one TPM you will not get an automatic warning as 10 psi is not enough to set off most sensors as many are sett for a 15% loss in air pressure. So with no warning you would need to be constantly taking your eyes off the road to read the tire pressure on each pair of duals.

 

Why are you having leakage problems with extenders but not with crossfire hose connections?

 

Crossfire only and no TPM will NOT give you a warning of a loss of air while traveling.

 

Just some thoughts.

I can set my TPMS to alarm less than 15%. It is a settable point based on PSI not a percentage. As and example I can set mine to alarm on a base 100 PSI tire pressure say 90 PSI on low end to 120 PSI high end. I have to check to see if my TPMS can alarm say at 95 PSI for the low setting but I think it can. Some may already know for sure and can respond with a better answer. I am sure there is a +/- tolerance to both Crossfire and TPMS and taking those both into account perhaps the whole thing is a worthless exercise I just don't know.

 

I am not sure why the Crossfire does not seem to have the leak problems we have experienced with valve extenders. Perhaps better quality I don't know but it seems to be the case. I don't have Crossfire's so have no personal experience just what I have been told so take that for what it is worth probably nothing.

[docj]

I am not sure why the Crossfire does not seem to have the leak problems we have experienced with valve extenders. Perhaps better quality I don't know but it seems to be the case. I don't have Crossfire's so have no personal experience just what I have been told so take that for what it is worth probably nothing.

 

My experience with valve extenders, particularly with long ones for inner duals, was that they could loosen (probably from vibration). I think the fact that the extensions are fastened to the Crossfire valve may simply resist the "twisting" motion which tends to loosen them. My previous Class C came with braided extensions whose valve ends were attached to the "can" around the axle hub and I never had leak problems with them. Maybe its something as simple as that.

[Jack Mayer]

OK, I'm confused. Do the Crossfires not come with their own extension hoses to get to the valves? I thought they did....

 

In the picture above, if one were using a single sensor would you still have the same two hoses with T's on them, and simply not use one of them? I cannot see the utility of having two sensors. IF the Crossfire balances across the tires why would you put a sensor on each line? It is just something else to leak.....

[docj]

OK, I'm confused. Do the Crossfires not come with their own extension hoses to get to the valves? I thought they did....

 

In the picture above, if one were using a single sensor would you still have the same two hoses with T's on them, and simply not use one of them? I cannot see the utility of having two sensors. IF the Crossfire balances across the tires why would you put a sensor on each line? It is just something else to leak.....

 

The regular Crossfires come with two braided hoses semi-permanently mounted on the main assembly just like the picture only without the T's. On the assembly there is one Shrader valve on which you can mount a single TPMS sensor. That valve is in the picture pointing straight at the camera.

[Jack Mayer]

Got it...thanks, Joel.

[Smitty77_7]

The other item I'll add, is that Park House Tires really had to really work to attach the Crossfires at an angle that would both allow good access to the single air valve, and yet have the air valve angled far enough away from the wheel hub to allow the TST sensor to attach. (They talked with Crossfire, and the gent on the phone gave them some different options to try.) 22.5 wheels Alcoa wheels.

 

The other tip, if you have roadside assistance, I've been told that some of the tire experts dispatched to assist - are not fond of working with Crossfires. This was second hand info, from the Park House Tire manager, who had customers come back in after road side tire changes to have their Crossfires remounted. (May be isolated cases, but worth knowing.)

 

And a lessons learned from me. I did 4 corner weight, and set tire PSI according to Tire MFG recommendations + 5 PSI for added weight contingency. This meant for our 22.5 x 12R's we ran with 105 psi in the duels. (I was within 400 lbs on the right side, so I jumped to the next higher PSI level setting from the tire chart, + my 5 PSI contingency.) So, my lessons learned - I bought my Crossfires for the 105 PSI settings. Since then, I've upgraded the coach from X2 8D's to X4 L16's on the passenger side, also on the passenger side, we've mounted X5 Solar Panels, and controller. We have not yet had a new 4 corner weight taken, but by my math, I've added between 450-550 lbs to the passenger side, with the 90% of that largely over the passenger duals and tags. This should have put me up into the next range on the tire chart, towards the lower 1/4 of the range. And remember I had jumped to this range due to being pretty close to top of the previous ranges scale. And yeah, I had the extra +5 PSI contingency.

 

I called Crossfire, and asked them their opinion on the down side of bumping my rear duals to 110 (did the same with the tag's too). They said just understand the visual PSI indicator would be off to the high side, and get used to that new level as being the norm. So lessons learned, before adding Crossfires, think about if you have any major weight adding enhancements ahead:)! I would have ordered 110 PSI Crossfires, if I had followed this input:)!

 

Best,

Smitty

[RandyA]

I made some additional photos of Charlie's Crossfire and TPMS today. He attached the main piece to the side of the hub cap. See below.

 

 

 

 

[Bob Cochran]

I am really having a hard time getting my mind around why one tire monitor is not workable and still need 2. I think if I understand this correctly; if you use one monitor you can lose pressure in one tire say inside dual and not the outside and you would not alarm, is the right? So if that happen could have a flat/or low pressure shredding or potential blow out without alarming. That sound right; of coarse the temperature monitoring be kaput but I always think that has limited use. other than advise of a potential say dragging brake problem, etc.

 

Sorry just not getting it I guess and really want to understand if I can get it through my thick skull!!!

[docj]

I am really having a hard time getting my mind around why one tire monitor is not workable and still need 2. I think if I understand this correctly; if you use one monitor you can lose pressure in one tire say inside dual and not the outside and you would not alarm, is the right? So if that happen could have a flat/or low pressure shredding or potential blow out without alarming. That sound right; of coarse the temperature monitoring be kaput but I always think that has limited use. other than advise of a potential say dragging brake problem, etc.

 

Sorry just not getting it I guess and really want to understand if I can get it through my thick skull!!!

 

If you lose pressure in one tire the Crossfire will isolate that tire after the pressure in the remaining one has dropped by ~10 lbs. I think that all you need to do is set the alarm on the TPMS so that it triggers with that same 10 lb drop. Then you will know that one of the duals is low.

[Bob Cochran]

So I was not confused then one sensor will work as long as you set to be alarmed at or below 10 psi. Thanks.

[spindrift]

I'm thinking about installing the Crossfire on my current dually P/U. Is it recommended to have metal stems installed before using the Crossfire system?

[Alie&Jim's Carrilite]

If you go back to post #15 and give Ed Donnely a call, they will make a set with shorter hoses for a standard pickup setup. Great guy to work with. Yes, it's recommended to use metal valve stems.

[spindrift]

Thanks.

[john lowry]

I have had Crossfire on my 4500 GMC for about 6yrs now & think they are great.I have noticed if you are parked out in the hot sun for a few hours you will see the color code change

[mohamer]

I am putting Cross Fire on my MH rear duals and will be putting one Pressure Monitor on the Crossfire per Dual wheel set.

I am going to set the alarm at the dual sets to alarm before the Cross Fire goes Black in color (separates the duals).

This way I can have the duals equalized with Crossfire and have them monitored with my TPMS. YMMV

[Tireman9]

Yes setting the low pressure warning at 5 to 8 psi below your set pressure is a good approach if you are not monitoring each tire.

 

I am still looking for information on the meaningful performance improvement or benefit to having this type of system on an RV.

[mpierce]

IF you do not have TPMS, then the crossfires allow you to easily check that both the drive wheels are correct pressure. If you do have TPMS, then they are not as useful.

 

On my Peterbilts and trailers, I found using crossfires increased tire life 20-30%, because the pressure on a set of duals was EXACTLY the same. But, on a MH, we usually age out tires before we wear them out, so that benefit is not so much of a concern.

[sclord2002]

One of the benefits to me, is that I don't have to remove the TPMs sensors to adjust air pressure and that I can fill both tires from one schrader valve. OK, I guess that's 2 reasons... also I like the visual pressure indication. Now we are up to 3 reasons. Anyway, after more than a year, I am pleased with them and can recommend them to folks who are inclined to consider them. I will be happy to discuss them with folks at the ECR. Charlie

[Alie&Jim's Carrilite]

I've had mine since December 2014, and the jury is still out. I've had to disconnect them several times and blow trash out of the lines. What happens is that over a period of time, the line creeps from yellow to red. But the TST shows the air pressure and temp to be different meaning that the equalizing part isn't working. I can remove them, blow some air thru the valves and reconnect them and their fine for awhile. What I don't know is if these tires were balanced using beads or something I don't know about causing this issue. The TST senders never fail so as I said, the jury is still out.

[Tireman9]

One of the benefits to me, is that I don't have to remove the TPMs sensors to adjust air pressure and that I can fill both tires from one schrader valve. OK, I guess that's 2 reasons... also I like the visual pressure indication. Now we are up to 3 reasons. Anyway, after more than a year, I am pleased with them and can recommend them to folks who are inclined to consider them. I will be happy to discuss them with folks at the ECR. Charlie

Since I recommend setting inflation 10% above the minimum needed to carry the measured max load on the heavier end of the axle, I find that I only need to remove my TPM sensors once a season so no big deal.

 

MPIERCE I can't argue against your data but I do know that it is easy to see significant variations in tire wear when you change tires as tire companies will change compound over the years it will take for you to wear out a set. I also know than in controleed testing on one seven mile stretch of roadway weather and load variation can cause significant variations. BUT if you feel you are getting improved mileage then I can't suggest you change your practice. Do you really think that a 2 psi change in air pressure (the amount you may set two different tires) will result in a 30% improvement iin wear? If so then simply increasing all tire pressure by a couple psi should result in a 30% wear improvement.

[porky69]

I will vouch for MPIERCE on this. I worked for a company that used a similar product (see http://www.linkmfg.com/products/cats-eye/) and the company bean counter had the documented proof that the trailers that had them got more tire life. The caveat to that is as a part of your preventative maintenance program you need to keep an eye on the hoses, making sure they are tight and not damaged.

 

As for documented fuel savings I have no idea, but proper tire inflation has been proven to affect fuel economy.

[Tireman9]

I can accept a comparison between units with a pressure monitor system vs units without any type of monitoring system.

 

This does not translate into better tire life or 30% better wear when the duals are matched inflation with Crossfire or similar system vs tires that are set with accurate gauge and an electronic TPM system is used to warn the driver of air loss.

 

If it could be shown that matching tire pressure actually delivered even 2% better wear in controlled testing all major truck companies would get such a system delivered OE.

 

We are looking at Correlation vs Causation. It is important to control all other variables or incorect conclusions can be reached.

Nothing against Crossover systems. Just haven't seen results from controlled side by side comparison. Maybe if someone ran a truck or RV with one side with cross over and other side without and did identical pressure monitoring for life of a set of tires we would have a nice comparison.

[porky69]

I forgot to mention that I learned quickly to not trust the "Cat-eye" for inflation pressure indication, I always put an actual pressure gauge on the central valve stem and just let it equalize the pressure from tire to tire.

 

That being said a set of equalizers combined with a TPMS system may provide maximum tire life and may give better fuel economy but, in the RV application tires are seldom miled out before they are timed out, and by that same token a small increase in fuel economy over relatively few miles(most RV'ers probably do less than 10,000mile/year vs trucking companies that do 10,000miles/month) does not provide for a great return on investment.

 

Peace of mind (safety) is the biggest return on investment that either solution(in RV use), each on their own or in combination, will result in.

[VegasFlyer]

The fundamental difference between using one or two TPMS sending units is, "probability" versus "possibility".

 

If you run two sensors, as shown in the picture, and one sensor gives you an alarm but shows a loss of 10 pounds, the probability is that you have two inflated tires with the one that triggered the alarm being 10 psi less.

 

If you run one sensor, as discussed, and that one sensor gives you an alarm, you could have the condition above, you could have one tire completely blown or somewhere between underinflated by ten pounds and totally flat.

 

It comes down to how important is it for you to know the difference. If you are just toolin down a nice lazy road, no big deal. If you are in heavy traffic with limited shoulders or places to pull off the road, it sure would be nice to know the whole picture of what is going on with your tires.

 

I have used the cross-fires on a couple commercial trucks and trailers and do like them a lot. IMHO the addition of being able to add the second TPMS adds a major level of comfort.