Tire pressures

[RVNeophytes2]

Originally Posted by Crasher

Go ahead and run your tires at max pressure and see how you like the ride. The best ride and control comes when tires are inflated correctly for the weight they are carrying. This holds true for any vehicle.

Bear in mind, the tire companies say that you'll have less than optimum traction while running over-inflated tires...

There is a reason the engineers label those inflation tables as optimum, not minimum.

[Gordon Dewald]

Originally Posted by flynnwalter

Gordon
I agree completely with your post about changing technologies enabling us to do so much more than just our fathers ever could. We are supposed to get smarter as we get older. Lord knows in my case that's a pretty low threshold for a challenge. But I now feel a responsibility to do what I can to safeguard my passenger(s) and those on the road around me, and do the homework necessary to take advantage of that technology in a safe manner. Few enjoy homework, but the attitude by some that we can operate a motorhome while blissfully ignorant is a scary thought. We are responsible--period.
You also wrote: "IMO the example of a rear axle being 2700 lbs heavier on one side than the other makes me think something is not right. I expect the MH manufacturer did not design or build the MH with a weight difference that large. I could find no information on the net to confirm that but that is about 10% of the coach weight." That is our coach and my challenge is for you to come to my house and reload any and everything we have put into our coach to redistribute the weight properly. We have 50 amps and water available in case it takes you more than one day. I will even buy you any dinner in town if you can get the rear axle weight difference below 500 lbs. I suspect you will find (as did we) that the MCC pillow arrangers held sway over their engineers and the layout in the basement precludes any significant weight redistribution. It is an excellent example of just what we write about with changing technologies above. Somebody needs to be in control who knows what he/she is doing. Fortunately, there are safe workarounds for our weight issue, and I believe we have made things not only safe, but now comfortable--we changed lots of things I have not mentioned. But it took doing homework and asking questions and yes, money. We are ultimately responsible for operating a safe vehicle. Once we are in a court of law, its a bit late to be thinking about what we should have done. But at this stage in life most important to me is my conscience and how I would feel if I caused injury or worse to another when I could have prevented it had I not been too busy to do my homework.
Frank W. 09 Cayman

Hey Frank;
Thanks for the offer. I just may take you up on it given the opportunity. We are planning to travel to you end of the world in the future.

I doubt there is much we could do to rearrange your goods on the frame to bring thing into balance. I doubt you put 2700 lbs of goods on one side without putting a like amount on the other. I sit and think about things and wonder what the manufacturer could put on the rear corner of the coach to make that axle that much heavier on one side than the other. After all the engine is in the center of the frame. I do not believe they have the fuel tank on that corner, or the water tank. Most of the heavy things would make sense to put between, on top or under the frame rails, centered. If the pillow arrangers had put all of the heavy stuff on the passenger side the passeger corner should be heavy as well.

If I recall correctly there is also a heavier weight on the opposite corner of the coach from the heavy rear side. Logic says IMO that either of the ride heights on the heavy corners could be high. If that were true then there is a possibility that the suspension could be changed to remove some of the corner.

Only other thing that would come to mind really quickly is the frame is bent. I have encountered that fairly often when managing projects with gravel hauls. Trucks raising the box would have to dump their air before raising the box to dump the load. It they did not the frame could get twisted. I know you do not have a gravel truck but the frame issue could be the same.

However on your assurance that the ride height it not an issue and assuming they have discounted any other mechanical issues with the coach I will acquiese to your experience.

I still hope the offer to stay is open. I hope we do not have the same issue with our coach when we do the corner weighing. Our grandson is a freightliner mechanic and assures us he will be able to get the corner weights and tag weights close. Fingers crossed.

[Ray,IN]

Originally Posted by RVNeophytes2

Bear in mind, the tire companies say that you'll have less than optimum traction while running over-inflated tires...

There is a reason the engineers label those inflation tables as optimum, not minimum.

Please link to one that says it is the optimum pressure recommendation.

[DriVer]

Originally Posted by oildriller83

If this is correct, why not fill your tires to maximum air pressure for maximum weight rating per tire manufacture specs?

We have gone round and round with this question typically winding up in a fur ball.

The Maximum Inflation Cold rating on the side of an RV tire is a benchmark limit.

Every expert that knows anything about tires including the actual manufacturers will offer that you need to weigh the RV and inflate the tires on each axle to the higher PSI for the actual weight that is measured. If one side is heavier than the other both tires on the same axle should be inflated to the same pressure. Looking at the manufacturer's inflation chart, use the rating for the next higher psi rating.

One big equalizer is to use a TPMS. On this site, TST has been one of the favorites. A TPMS will tell you at a glance what the pressure at each wheel end is plus the temperature in the valve stem. A low pressure situation will always result in higher heat than the other tires being monitored. When properly set, the TPMS will warn for both Low/High Press and Hi Temp.

Using a strategy where tires are inflated to their maximum pressure cold is not reliable. Question arises what happens if the tires leak down? It is logical that you would have to air up the tire. therefore if you still have to air up the tire, why not start with the ideal inflation pressure for the maximum load on the tire?

[flynnwalter]

Gordon
After our modifications (Source Ride Enhancement kit & trailing arms, stepping up two tire sizes and more) we are okay with the 2700 lb heavier passenger rear. Good, since we can't do anything much about it and we can't afford another coach! The main reason I post ad nauseam about the 2700 lbs is to let coach owners know how important a four corner weighing really can be. Without it, we would be seriously under inflated on those old 255/70R22.5 GYs that were already perhaps too near their max rating even without the extra 2700 lbs on one corner. Corner weighing usually only has to be done once, but without it folks are really just guessing both sides of an axle weigh the same when they divide the total axle weight by number of tires. That is my message, but I do appreciate your concern and wanting to help. I will send you a PM detailing just what is above and below the heavy corner if you wish, don't want to bore everyone else with a long list.

[Crasher]

Ok, enough already. The tire pressure topic is exhausted. I wonder how the Green Bay Packers are going to be this year?? As long as they beat the Bears and Vikings, it'll be a good season.

There, the tire thing is dead.

[ru499]

Originally Posted by 336muffin

I know I will be burnt for this but..............when a tracter and trailer rig cross' s the US with 10,000 pounds and then comes back with 48,000 pounds do they adjust tire pressures? No. I'm just giving something to compare.

I agree being a truck driver. This 4 corner weight thing is ridiculous. . My truck tires carry 80000 lbs and last over 150000 miles. How about when the road is crowned? Should you pull over and adjust the pressure???

[Gordon Dewald]

Originally Posted by flynnwalter

Gordon
After our modifications (Source Ride Enhancement kit & trailing arms, stepping up two tire sizes and more) we are okay with the 2700 lb heavier passenger rear. Good, since we can't do anything much about it and we can't afford another coach! The main reason I post ad nauseam about the 2700 lbs is to let coach owners know how important a four corner weighing really can be. Without it, we would be seriously under inflated on those old 255/70R22.5 GYs that were already perhaps too near their max rating even without the extra 2700 lbs on one corner. Corner weighing usually only has to be done once, but without it folks are really just guessing both sides of an axle weigh the same when they divide the total axle weight by number of tires. That is my message, but I do appreciate your concern and wanting to help. I will send you a PM detailing just what is above and below the heavy corner if you wish, don't want to bore everyone else with a long list.

Hey Frank;
Fire away with the numbers. This is one topic that has piqued my interest.

[Crasher]

Originally Posted by ru499

I agree being a truck driver. This 4 corner weight thing is ridiculous. . My truck tires carry 80000 lbs and last over 150000 miles. How about when the road is crowned? Should you pull over and adjust the pressure???

This really is getting old. So you are saying that it was ridiculous for me to find out from a six position weight that the front right was loaded to almost 400# over the tire rating at max pressure of 120 psi. You say it would have been ok to run that tire overloaded until it blew out and caused damage or even worse? I somehow feel that I'm better off now with it loaded 400# less than it max, but what do I know, I wasn't a truck driver with a tire thumper.

[Gordon Dewald]

Originally Posted by ru499

I agree being a truck driver. This 4 corner weight thing is ridiculous. . My truck tires carry 80000 lbs and last over 150000 miles. How about when the road is crowned? Should you pull over and adjust the pressure???

Another interesting topic. Roads are crowned at 2%. Theoretically the slope will shift the weight to the low side. However since you are likely at max pressure there is nothing to be done in your case. Some owner operators I know would put the older higher mileage tires in the inner side to account for road crown.

As well when you were hauling OTR you were more concerned with front to back loading so each set of axles were not overloaded. Bad when going over the highway scale.

Side to side loading depended upon what you were pulling. If you were pulling highboy and hauling something like lumber or equipment you centered the load as best you could and still at max pressure were more concerned with front to back axle loading. Lowboy hauling equipment you centered the equipment and again did the front to back load. Box van depended upon the product being loaded and when it was dropped off. Last on - first off. However you still tried to load evenly.

In my juridiction when I was working the Transport officers had mobile wheel scales in addition to the fixed weight stations we are familiar with. In those days there was no regulation for side to side loading, just axles but the capability was there to write tickets for overloads on a set of wheels. Not sure what the law is now as I have not been following the regulations.

In OTR you carried the load and it changed weekly or even daily causing wear patterns to average out. Coaches live with the weight distribution for their entire life. True it changes a bit from one trip to another but they are insignificant. Therefore a four corner weight can have some import and long term consequences.

[ru499]

To be honest, if my steer tires only had 400 lbs till overloaded, I'd get a higher load range tire if possible.

[Coma]

While there are many things we can learn from the OTR driver, you must take into account that they are different vehicles. Trucks, by design, are constructed symmetrical side to side. MH's are not. It would be unwise to ignore their differences and overload a tire.

[Crasher]

Originally Posted by ru499

To be honest, if my steer tires only had 400 lbs till overloaded, I'd get a higher load range tire if possible.

That would be fine, but only mask the real problem which was an improper ride height at a rear corner. Now both are 4-500 below max. Also, I could not clear larger tires when in a tight turn and incline.

[DMTTRANSPORT]

Here's how I roll every day with no worries if I am heavier on one than the other, If there is NOT an issue here there's defiantly not one on your Coach!