Dual wheels question

Reniram · 10-10-2019, 01:29 PM

I was talking to an old friend and found that he too was an RV er and the discussion turned to the handling of the Rv ..His rig is on a Chevy (c) class chassis and mine being the Ford F53...He wanted a better ride and was looking at changing sway bars.experimenting with tire pressures etc..then he came across the Crossfire air equalizing system and installed them and now he swears that it has improved so much he is not even looking at any other modification...Has anyone else put these on their duallies and got similar performance..The premise is that with road surfaces being uneven and going into a turn, one of the tires is subject to more force than the other even though they are on the same axle..so with the air equalizing feature both tires are giving maximum grip to the road surface and sway and driveability is greatly enhanced...I was looking to install another rear swaybar on my rig but the cost was pretty high..these things run around $130.00 which is a significant difference....

thompwil · 10-10-2019, 02:39 PM

Good question, I too have been considering them for our F53 after observing how the tire pressures behave when we got our TST TPM system. Driving the interstates at 65mph, the inner rear tires on each side will increase in pressure by anywhere from 5 to 12psi more than the outer tires. I’m a fanatic about proper tire pressures and check them before hitting the road with a digital gauge, and note the TPMS is matching the gauge. I have no idea if this effects handling or not, or if it’s even worth worrying about, but would be interested in feedback from users too. The inner tires would seem to be carrying more load at that point. We did put 7k miles on it before knowing this and had no problems. I’m happy with our TPMS, but it did give me something else to think about.

I would need to get four pass through pressure sensors and plumb them in on the tire side of the equalizer for proper safety monitoring. I believe the center caps may need modified too in order to mount the devices.

akeagle · 10-11-2019, 12:02 AM

On our trip to the Lower-48 and back this year I was surprised at the large variations in tire pressures over each day as indicated on our TPMS. This was mostly early in the day but it was not always in response to warmup or ambient air temperature. It seemed to settle down about halfway through the driving day and the temps became more consistent and always within normal perimeters. There were sometimes some instances of the "hot sun" effect, but not as much as I've seen before and part of our trip was in the SouthWest in good weather with temps over 100. Much of our trip both down and back home was in the rain, so perhaps that might have something to do with the pressure variations as well as the air temp.

As one can see on this thread, some of us are literally obsessed with maintaining tire pressures while others have a "set it and forget it" attitude. Since I have a TPMS I don't worry about the pressure variations because I know there are a lot of variables that affect them. As long as the high and low perimeters are not exceeded, I don't get overly concerned.

thompwil · 10-11-2019, 08:41 AM

Quote:

Originally Posted by akeagle

As one can see on this thread, some of us are literally obsessed with maintaining tire pressures while others have a "set it and forget it" attitude. Since I have a TPMS I don't worry about the pressure variations because I know there are a lot of variables that affect them. As long as the high and low perimeters are not exceeded, I don't get overly concerned.

Being safety conscience is not such a bad thing, I wouldn’t call it an obsession. Being an avid RVer for over 35 years teaches you what to attend to. This is my first season with an aftermarket TPMS, and I’m gaining faith in it to rely solely on the readings which are proving to be reliable and accurate.

My main reason for responding was to note my personal observations, and express interest in others experiences with said devices too. The claims made by the manufacturer do make sense as far as load management and tire wear goes, the handling part is a curiosity for me though. The rear tires on my 2014 Ram Dually didn’t behave the way the rears of the MH do (it had a factory TPMS). Only 1 or 2 psi difference between inner and outer depending on sun, etc. I was a bit surprised by the behavior MH rear tires which could very likely be quite normal.

BROAD ST · 10-12-2019, 06:45 PM

I have a winnebago intent 26m on the f53 chassis,put these crossfires on before our trip to yellowstone from va,really like them,still think im going to put a rear trac bar on.

Reniram · 10-13-2019, 05:01 PM

Quote:

Originally Posted by BROAD ST

I have a winnebago intent 26m on the f53 chassis,put these crossfires on before our trip to yellowstone from va,really like them,still think im going to put a rear trac bar on.

Thanks for the feedback..I stepped up and purchased a set of Crossfires and installed them just today so I have not had the opportunity to test them out....I am hoping to recognize a change but I am not holding my breath.. I was not unhappy with our rig before...but a friend installed them and supposedly was very impressed with the better handling of his rig...

thompwil · 10-14-2019, 06:59 AM

How do they mount to the hub? and do you have any pressure sensors plumbed in?

Thanks
BT

Reniram · 10-15-2019, 03:42 PM

Quote:

Originally Posted by thompwil

How do they mount to the hub? and do you have any pressure sensors plumbed in?

Thanks
BT

You choose what tire pressure you need for your particular rig..mine are 80psi..they come in different psi kit form..
There are two supplied mounting brackets and you choose which one fits the best..The bracket is simply held on by one of the two chrome nuts that holds the rim embellisher on.. .They have an instant color readout feature..red is overinflated black is under and yellow is correct...I don't have a tpms on the rig ..there is one schrader type valve which supplies equal pressure to both rear wheels so you inflate until the yellow window appears and thats it...I probably won't be testing it out for a while so I still can't say if the ride / handling is any better

**creativepart** · 10-15-2019, 04:26 PM

Correct Tire pressure is vital for safety and does effect ride quality. It’s true the Crossfire system would help equalize dually tire pressures, for sure.

But in and of itself I fail to see how it could improve overall ride. Certainly not any more than setting proper tire pressure individually could.

The one shortfall in the system is that it replaces individual TPMS readings on each tire for one reading for both tires. I’m aware that in the event of a blowout the system will seal off the deflating tire from the good tire but then your TPMS is unaware that one tire has deflated and so it cannot warn you.

thompwil · 10-15-2019, 04:49 PM

When, and If, I install a set, the plan was to get four TST flow through sensors and attach directly to the schrader valves on the wheels, then attach the lines from the Crossfires to the sensors. This will still give individual alarms if a tire fails, at least that's the thought anyway. The flow through sensors would be an additional 200 bucks for four of them to replace the cap sensors. I'll contact both companies first before doing this to make sure there isn't some reason not to. This will probably go on my next Spring to-do list though.

Reniram, thanks for the info on the mounting.

Tireman9 · 10-16-2019, 04:20 PM

Quote:

Originally Posted by thompwil

Good question, I too have been considering them for our F53 after observing how the tire pressures behave when we got our TST TPM system. Driving the interstates at 65mph, the inner rear tires on each side will increase in pressure by anywhere from 5 to 12psi more than the outer tires. I’m a fanatic about proper tire pressures and check them before hitting the road with a digital gauge, and note the TPMS is matching the gauge. I have no idea if this effects handling or not, or if it’s even worth worrying about, but would be interested in feedback from users too. The inner tires would seem to be carrying more load at that point. We did put 7k miles on it before knowing this and had no problems. I’m happy with our TPMS, but it did give me something else to think about.

I would need to get four pass through pressure sensors and plumb them in on the tire side of the equalizer for proper safety monitoring. I believe the center caps may need modified too in order to mount the devices.

Inner dual will always run hotter due to less cooling air getting to the tire and wheels.

Tireman9 · 10-16-2019, 04:24 PM

Quote:

Originally Posted by creativepart

Correct Tire pressure is vital for safety and does effect ride quality. It’s true the Crossfire system would help equalize dually tire pressures, for sure.

But in and of itself I fail to see how it could improve overall ride. Certainly not any more than setting proper tire pressure individually could.

The one shortfall in the system is that it replaces individual TPMS readings on each tire for one reading for both tires. I’m aware that in the event of a blowout the system will seal off the deflating tire from the good tire but then your TPMS is unaware that one tire has deflated and so it cannot warn you.

I agree, As a tire engineer I do not see how constantly "balancing" the pressure would result in a significant or maybe even measurable improvement in ride & handling. Especially considering that a majority of the ride disturbance for the driver would come from the front tires.

Bet that in a "blind" controlled tedt. it would be unlikely to find any repeatable difference.

jarnarcos · 10-16-2019, 04:28 PM

Quote:

Originally Posted by BROAD ST

I have a winnebago intent 26m on the f53 chassis,put these crossfires on before our trip to yellowstone from va,really like them,still think im going to put a rear trac bar on.

Rear track bar (supersteer) makes a huge difference in stability. Much less back and forth when the 18 wheelers go by.

jadatis · 10-17-2019, 03:48 AM

Dual used tires need higher pressure to compensate for roadcurve, but because axle-weight devided over 4 tires, dont always need max allowed pressure of tire.

An extreme fictiv example:
If pressure verry much to high for the weight, at a larger roadcurve, only the inner tires on the ground, and outer tires not touching the ground.

Ofcource this will never happen in real live.
But if deflection of tire is more ( but within safety standards) the inner tire will deflect more and by that more weight is transported to outer tire.
This then would give more equall heatproduction, so more equall temp and pressure in tires.

To determine if you used to high pressure, wich could also explain the difference in temp, you should do the weighing procedure as often described, and let me calc a pressure for that.
Then compare that to what you used, and mayby part of temp- difference can be explained by that.

Completely the same pressure is impossible, but reduction of difference mayby.

If now you use an air equalising system, i think its a little hose that connects the 2 valves, then by more deflection of inner tire, the air is going to the outer tire, wich then deflects less, and it has same effect on division of weight.
But still more heatproduction of inner tire then outer, for that deflection counts.
Mayby then you can use more pressure, and still better divission of weight, so lesser heatproduction in total, so lower warm pressure and lesser temp- so pressure -difference between inner and outer tire.

jadatis · 10-17-2019, 05:20 AM

Realise that , the more things you put on, the more things can fail. Then for tires, you might yust create pressure-loss, by all the hoses and sensors you screw on them.
In the end your attention is yust to much to these devices, that you loose checking what is basically important.

One example is lowering cold pressure to advice on a hot day of 95 degr F, dont do it, gives more heatpeoduction.

Tireman9 · 10-19-2019, 08:54 AM

Dual application needing higher inflation is not quite correct. Tire load / inflation tables clearly identify the correct inflation for that tire position with both tires being set with your hand gauge to the same pressure. Most people can match the inflation at +/- 1 or 2 psi. Nowhere in industry standards does it say the two tires must be matched exactly when running.
People are IMO paying entirely too much attention to the details of the TPM numbers. We need to remember it is just a warning system for when / if a tire starts to lose pressure.

Jim_HiTek · 10-19-2019, 11:33 AM

Speaking of stability while on the highway...

Sway from passing vehicles, going the same direction or opposite, in my case was pretty much eliminated by using those plastic V-spoiler devices...aka Air Tabs. They're vortex generators and help decouple the winds slipstream the RV creates from the RV. So less tendency to rock.

My '02 Winnie seemed to want to rock back and forth from passing vehicles or from quartering winds. At the time back in 2016-17, I didn't care for the white knuckle grip I had on the steering wheel before the tabs and after adding the tabs don't even think about it when a big semi approaches.

I'm a big fan now and the $200 cost is around 20% of the cost of sway bars which makes them well worth it, IMO. I did write up an article about them after installing them nearly 3 years ago and the company provided the V-Spoilers to me for free for ad space on my blog but they never bothered to create an ad. Shrug. Anyway, here's my eval: V-Spoiler