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Old 10-08-2020, 01:37 AM   #41
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Old 10-08-2020, 01:57 AM   #42
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Originally Posted by jabrabu View Post
I haven't weighed mine, but I have seen weights from other class C's with the same length and similar floorplans. They are generally close to or over the ratings for both the rear axle and rear tires.

I'm not sure actual weights would change my tire choice. I want the most durable tire I can get. For that tire size (225/75R16), load range E 10-ply tires seem to be the best you can get. Load range E is rated for 2680 lbs.

I had a small Class C that, when I weighed it, was almost at the maximum weight with basic provisions and no water. It was a tail dragger. So I added air bags and safety steer. What a difference in handling. The tires I did not trust. I went in to have them looked at. They called me to come see them. They were in the parking lot next to the RV. Well they looked good. The service rep asked me to put my nails into the inside side rear tires side walls. They were like gelly and I could see the cord. I replaced them with Firestone tires and never had a problem. I aired the tires up to the Firestone load/pressure chart. They were good tires.
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Old 10-08-2020, 10:43 AM   #43
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Well....I appreciate that you called me a decent guy! LOL

Advice and opinions on here are like noses, we all have them so we all have to do our own research before taking someone's advice. Hopefully the more advice and options we all ask for and give will help guide us to the right conclusions.

All I can provide is the following and then everyone can do their own research and make their own informed decisions:

1) I have my Crossfire Indicators mounted off a lug nut and have no signs of a balance issue. My installation would cause more of a balance issue than having it mounted closer to the center of the wheel.

2) While balance can have an impact on tire wear, it is usually very minimal with most abnormal tire wear being caused by improper tire pressures and alignment.

3) Take a close at most big rigs carrying heavy loads and you will they use a Crossfire or similar system because of the importance of dual tires having equal pressure carrying those loads to promote proper tire wear and minimize the chance of a premature blowout.

4) It is almost impossible to keep all four dually tire pressures equal so that the tread can perform its load carrying ability properly. Inside tires are against brake drums / rotors that radiate a lot of heat. Heat increases tire pressure. One tire will also sometimes be close to the exhaust pipe adding more heat. Inside tires cool less than outside tires at highway speeds as well. When dually tire pressures are unequal, it will cause abnormal tire wear and can lead to potential tire failure.... back to the OP's original post.

5) It is my opinion from the research I have done that it is far more important to ensure that all four rear tires are equally pressurized than to worry about a slight balance issue. Having all four tires equally pressurized will ensure each tire's surface is properly contacting the road surface and carrying its share of the load equally. Bottom line.... the rear tires will wear and perform optimally and guard against a premature failure.

6) A picture is worth a 1000 words....

But this picture is not realistic, so to my opinion worthless.
First the inner tire is placed higher.
A real picture would be realistic, and then you would see that the inner tire pushed some air to the outer tire, but pressure in tire the same.
So to my conclusion effect is practically zero.


If TS gives real weighed loads on axle ends in the loading as going on trip, and tire-specifications, I can calculate a save pressure at wich most likely the treath separation wont happen again. Then it would probably explain the failing tires.



Where they always on the same side? I expect it , because weightdivision stays mostly the same for a RV trough the years.
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Old 10-08-2020, 11:51 AM   #44
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Originally Posted by jadatis View Post
But this picture is not realistic, so to my opinion worthless.
First the inner tire is placed higher.
A real picture would be realistic, and then you would see that the inner tire pushed some air to the outer tire, but pressure in tire the same.
So to my conclusion effect is practically zero.

If TS gives real weighed loads on axle ends in the loading as going on trip, and tire-specifications, I can calculate a save pressure at wich most likely the treath separation wont happen again. Then it would probably explain the failing tires.

Where they always on the same side? I expect it , because weight division stays mostly the same for a RV trough the years.
I believe the picture is exaggerated to make a point.

First, the road surface is basically an upside down V. The center is the highest point with a gradual slope down to the berm on each side of the road to allow rain water to drain off the highway to minimize hydroplaning.

As you change lanes you have a set of tires on each side and the inner tire will be higher than the outer tire as a result of the road slope. Your axle is not going to bend to try and keep each tire "level" so to speak.

Beyond that..... it is simple physics that temperature impacts pressure. In most instances, the inner tire runs hotter than the outer tire and it can be by several PSI. The more traffic and resulted breaking that is occurring, the more heat radiating from the brake rotor / drum and the higher the pressure becomes on the inner tire compared to the outer tire.

Once the inner tire becomes over-inflated, the center of the tire starts carrying the bulk of the load and the tire center begins to wear more than the rest of the tire. The outer tire being at a lower pressure has a different amount of tread contacting the road. Now there is an imbalance in the performance and wear between the inner and outer tires.

Here is another factor regarding as to how much temperature can impact the pressure of tires and the pressure differential of the rear tires.

Unless you only inflate your tires with nitrogen, which minimizes the amount of water vapor inside the tire, there could be significant changes in tire pressures as temperature changes based on the part of the country you live in.

If you live in Florida or another part of the country with high humidity and you are not using a dryer / desiccant inline your compressor air hose, you are putting a lot of water vapor inside the tire when you inflate it or add air to it. As temperature increases, the water vapor will expand at a higher rate than just nitrogen and oxygen causing greater increases in pressure.

If you live in Phoenix where there is less humidity, there is less water vapor in the air so the increase in pressure resulting from increased temperature can be less pronounced.

What I can attest to is that after using the Crossfire system, my inner and outer tires are at equal pressures and temperatures regardless of the driving conditions. As a result I am ensuring that my tires have the best change for equal wear and performance.
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Old 10-08-2020, 01:43 PM   #45
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I found a post on another forum where the owner had a Chateau 31E weighed. This was with a full 55 gallons of fuel and the 40 gallon freshwater tank full.



Total weight was 14,620. (GVWR is 14,500.) Front axle was 4,580 and rear axle was 10,040. So the rear axle is already overloaded from the factory, and there is no payload capacity. You can dump 300 lbs of freshwater, but that only helps a little bit. We often camp at state parks that only have electric service, and we prefer to arrive with a full tank of clean filtered fresh water.


Also, Ford specifies that at least 1/3 of the vehicle weight should be on the front axle, but the RV builders don't build them that way.
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Old 10-08-2020, 02:25 PM   #46
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I found a post on another forum where the owner had a Chateau 31E weighed. This was with a full 55 gallons of fuel and the 40 gallon freshwater tank full.



Total weight was 14,620. (GVWR is 14,500.) Front axle was 4,580 and rear axle was 10,040. So the rear axle is already overloaded from the factory, and there is no payload capacity. You can dump 300 lbs of freshwater, but that only helps a little bit. We often camp at state parks that only have electric service, and we prefer to arrive with a full tank of clean filtered fresh water.


Also, Ford specifies that at least 1/3 of the vehicle weight should be on the front axle, but the RV builders don't build them that way.


Agreed.... Myself and others have regularly posted that a Class C on a van chassis that is 25' feet or more is pushing the limits of the chassis. If you are doing short weekend trips you will probably be fine and happy and not experience any major issues.

However, as I become more educated about RV construction I learned that there was no way I was going to keep our Class C Outlaw 29H and do the long trips out west we were planning. Fully loaded we were at or over the GVWR and axle loads and I did not feel comfortable traveling thousands of miles and through the mountains with a coach that was at its limits before we pulled out of the driveway.

I was less concerned about the physical axle because they are rated higher than than the GVWR limits but the tires were the real concern followed by the suspension and brakes. The stock LT tires are at their limits and were never meant to carry a heavy load full time. That is why I recommend that if people with Class C's want to do one upgrade and one upgrade only, it should be moving to a commercial rated tire designed to carry heavy loads full time and have a higher weight rating.

I have since moved to a Super C on a heavy duty truck chassis that was better designed to carry the load and load balance of these big coaches. Had I done a better job of doing my homework before buying my Class C, I likely would have not gone that route once I realized most Class C's are on the ragged edge of being overloaded before you head out on a trip..... unless you want to travel with no water, no propane and only a 1/4 tank of fuel.
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Old 10-08-2020, 02:31 PM   #47
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Agreed.... Myself and others have regularly posted that a Class C on a van chassis that is 25' feet or more is pushing the limits of the chassis. If you are doing short weekend trips you will probably be fine and happy and not experience any major issues.

However, as I become more educated about RV construction I learned that there was no way I was going to keep our Class C Outlaw 29H and do the long trips out west we were planning. Fully loaded we were at or over the GVWR and axle loads and I did not feel comfortable traveling thousands of miles and through the mountains with a coach that was at its limits before we pulled out of the driveway.

I was less concerned about the physical axle because they are rated higher than than the GVWR limits but the tires were the real concern followed by the suspension and brakes. The stock LT tires are at their limits and were never meant to carry a heavy load full time. That is why I recommend that if people with Class C's want to do one upgrade and one upgrade only, it should be moving to a commercial rated tire designed to carry heavy loads full time and have a higher weight rating.

I have since moved to a Super C on a heavy duty truck chassis that was better designed to carry the load and load balance of these big coaches. Had I done a better job of doing my homework before buying my Class C, I likely would have not gone that route once I realized most Class C's are on the ragged edge of being overloaded before you head out on a trip..... unless you want to travel with no water, no propane and only a 1/4 tank of fuel.

Yeah, a super C would be nice, especially since we often pull a toad behind us. But they cost about twice as much as an E450 class C. I would expect them to be more expensive, but surprised that it's double.
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Old 10-08-2020, 02:35 PM   #48
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Yeah, a super C would be nice, especially since we often pull a toad behind us. But they cost about twice as much as an E450 class C. I would expect them to be more expensive, but surprised that it's double.
The chassis is a big part of that cost increase:

- Diesel Power
- HD Transmission
- Heavy Duty Axles, Brakes and Suspension
- 19.5" or larger commercial truck rated tires
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Old 10-08-2020, 02:49 PM   #49
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It's true that they cost more...

But how much are you willing to pay for your safety?
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Old 10-08-2020, 02:58 PM   #50
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Sometimes you find question about if pressure chanched when you put fi 65 psi in tire off the ground, and then load it. And endconclusion is always no.
So connecting the inner and outer tire with a tube, is only handy for filling the tires with exactly the same pressure. But on a sideward curved road, it has no or marginal influence on how the load is devided.
Probably even no air is transported from inner to outer tire.

And overloading rear axle is not only class C related.
But if overloaded, and tires are yust enaugh for the GAWR , then you better use higher pressure then belonging to loadrange.
I know , not allowed ( anymore) , but better then tire-failure.
Upgrading tires to more maxload then is the best solution.
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Old 10-08-2020, 03:04 PM   #51
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It's true that they cost more...

But how much are you willing to pay for your safety?

About $250.
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Old 10-08-2020, 03:30 PM   #52
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. We can dream: can't we?

Yep, and my “dream” doesn’t include duallies.

SRW on smaller rigs solve a lot of problems, plus they look better and weigh less.

It’s one of the features I like best on most Euro motorhomes, and hope Thor keeps it at least on some models when they eventually roll out Hymer USA. Not holding my breath though.
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Old 10-08-2020, 03:39 PM   #53
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The influence of water is also exagerated often.
Even if you put a gallon of liquid water in a tire, at 212 degr F ( boiling point at ambient pressure of 14.7 psi) , the extra pressure for the waterpart is max 14,7 psi.
OK, thats a lot on 65 psi, but it then gives lesser deflection,so lesser heatproduction then dry air, wich is positive for the temp of rubber of tire.

And for 162 degrF in tire only 5 psi extra rising of pressure by the water.

Filling tires with a compessor with vessel, then first give vessel highest pressure it is allowed, then fill the tires to needed pressure.
The watergas then condenses to liquid, wich you can drain, or uf not, wont go in the tire, and tou have less then 1% water as gas in the tire. And this is only if you dont want the pressure rising by water.
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Old 10-08-2020, 03:46 PM   #54
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Yep, and my “dream” doesn’t include duallies.

SRW on smaller rigs solve a lot of problems, plus they look better and weigh less.

It’s one of the features I like best on most Euro motorhomes, and hope Thor keeps it at least on some models when they eventually roll out Hymer USA. Not holding my breath though.
Perhaps it's possible to import a "Euro-RV"; that meets your standards...
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Old 10-08-2020, 04:06 PM   #55
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I was just interested in how all this became an issue. Doesn’t the lower DRW tire load rating versus SRW load rating already take most of these variables into account?

I trust it’s been analyzed to death by tire manufacturers who know quite a bit about tires.
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Old 10-08-2020, 04:16 PM   #56
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The Crossfire system might be worth it just for the extra convenience of checking and adjusting pressures. Even with valve extenders the dually valves are tough to get to, and you have to check and adjust 2 rear tires per side. With the Crossfire you have a quick visual to see that they are close to spec, and if you want to adjust pressure it's just one easily accessible valve per side.
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Old 10-08-2020, 05:04 PM   #57
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I like the idea of only having to monkey around with one tire valve stem..
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Old 10-08-2020, 06:08 PM   #58
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I pulled this from a tire manufacturer..... you can interpret it as you like.


Too Much Pressure or Over Inflation

An over inflated tire is stiff and the ride will be rough. They don't give in much to bad road conditions and the size of its footprint in contact with the road is less than what the tire manufacturer intended when the tire was designed. If a vehicle's tires are overinflated by 5 psi, they could be more easily be damaged when running over that pothole you didn't see or the debris in the road you didn't see.


After starting out with both tires at equal pressure I have seen the inside tire 5 PSI higher than the outer tire in addition to it running hotter than the outside tire in certain driving conditions. Given the above explanation of a tire that is over-inflated by 5 PSI, it stands to reason that the two tires are not performing equally under the same loads and conditions. And if you put enough miles on under those conditions, the tire wear between the two tires will not be equal.

Since installing the Crossfire, both tires pressures are always equal and at the same temperatures. Bottom line is that is good enough for me.

And Bob makes a great point. Only having to aid air to one valve stem and getting to the exact same tire pressure in both tires is a real bonus.
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Old 10-08-2020, 06:18 PM   #59
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Judge,
Would you please post that Crossfire web link one more time?
(I'm ashamed to admit that I don't have the time to go hunting for ittoday... )
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Old 10-08-2020, 06:22 PM   #60
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Judge,
Would you please post that Crossfire web link one more time?
(I'm ashamed to admit that I don't have the time to go hunting for ittoday... )
Anything for you Bob!

Crossfire - Dual Dynamics

I bought mine here you but can find them at many online retailers. This link is for the option when you are also using an aftermarket TPMS so you can install the sensors... but it will still only have one valve stem to add air to both tires.

https://truckpartsworld.net/shop/?sw...20tpms%20ports
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