What's my tire pressure????

[LVRVLUVR]

so heres what "I" did and why....

my tires have a maximum air pressure of 125 psi

the charts say less than 80 psi to be at weight...

I set all 6 at 100 psi

that puts my front @11,250 and rear @22,100

I'm a firm believer to not lower air pressure to make a smoother ride

I can't load anymore pics here so you have to believe what I'm say'n

when I get down to 85 psi... the side walls are buldgeing out...
they look low of air....

with the tire being designed to be at 125 psi...that's down 40 psi

also with it that low steering and handling problem are sure to follow...


if I remember correct when I did this almost 10 yrs ago...
I did some adjusting on the air bags to improve the ride...




lol.... but don't remember what I did

[LVRVLUVR]

Weighing Your RV


Your RV must be weighed when it is fully loaded. This includes passengers, food, clothing, water, fuel, supplies, any towed vehicles behind a motorhome, and the tow vehicle for an RV trailer. It is important to weigh your RV at a location that can provide axle-end specific weights. You should not expect to measure equal loads at both ends of the same axle, because floor plans and component locations vary significantly, however, you should distribute the load to obtain the best balance possible.
Use the following guidelines to ensure proper tire inflation pressure for motorhomes and RV trailer tow vehicles:

• Determine the heaviest end of each axle and use that load to select the inflation pressure for all tires on that axle.
• Refer to the appropriate Goodyear load and inflation table and select the inflation pressure for the load that is nearest to, but not less than, the load you measured, by moving up the table to the pressure line. Note that load and inflation tables include separate information for single and dual applications. For single applications, you can use the measured information directly, while for dual applications, you will need to divide the wheel position load you measured by two, then enter the table.

Some places where you can weigh your RV:

• RVSEF Weight & Tire Safety Program a service offered at many RV rallies and shows
• CAT Scales
• Weber Son & Service Repair Inc.
• Truck stops
• Farm co-ops or feed mills
• Some sand and gravel yards

Special Considerations

Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up.
Load Carrying Capacity

Single Versus Dual Tire Capacity Difference
A tire mounted as a single can carry a greater maximum load than the same tire mounted as a dual. This is because tires in a dual set will carry unequal loads due to differences in the crown of the road. Tire to tire inflation pressure and tire diameter differences also factor into the difference in load capacity.


Some places where you can weigh your RV:

• RVSEF Weight & Tire Safety Program a service offered at many RV rallies and shows
• CAT Scales
• Weber Son & Service Repair Inc.
• Truck stops
• Farm co-ops or feed mills
• Some sand and gravel yards

RV Inflation Guide>
Download Load Inflation Table>
Download RV Tire & Care Guide>

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[Waiter21]

Excellent, Sounds like you have it under control.

[LVRVLUVR]

Originally Posted by Waiter21

Excellent, Sounds like you have it under control.

thanks for all the help...wish I could show what the tire looks like

I'm sure i'll be play'n with it more

[jadatis]

made a picture of part of pressure loadcapacity list I made with extra save formula.
You will notice that in the lower pressures lower loadcapacity's then the official lists.
Your problemm with your picture quotum for this topic can be solved by storing picture on server-site or as I did on my one-drive that belongs to my hotmail-adress and copy the url .


top is dual and highlichted bottom is for single load .
Given per tire as is usual in America.

Ad first 10% reserve to the weighed loads before looking back the loads in the list . Then reserve for unequall load R/L and still acceptable gripp and comfort.

[Ray,IN]

Originally Posted by Waiter21

The maximum weight your tire will handle in a single mode is 7000 lbs, But it must be filled to at least 120 psi to do this.

HOWEVER - that's a cold pressure - what happens when the tire gets warm and the pressure goes up, You've just exceed the maximum pressure for that tire.

You are misinterpreting tire pressure when at operating temperature. Tire mfgrs. design and build that higher operating pressure into tires. ALL tire pressure recommendations are for cold readings. Operating temperatures will exceed sidewall listed pressures safely.
For your edification, email Firestone, Goodyear, Michelin, etc. and ask them to explain your understanding of tire pressure exceeding the maximum when at operating temperature.

[Waiter21]

Ray, Yes, I understand the tables are for cold temperatures.

In your opinion, what is the maximum tire pressure?

[jondrew55]

Originally Posted by LVRVLUVR

thanks for all the help...wish I could show what the tire looks like

I'm sure i'll be play'n with it more

So after all these math gymnastics, are you going to run lower or at the placard recommendations? Since you're running slightly larger Michelins than the original Goodyears I'd think you could go a bit lower but like that comment in the Goodyear literature said there would be little to gain.

[LVRVLUVR]

Originally Posted by jondrew

So after all these math gymnastics, are you going to run lower or at the placard recommendations? Since you're running slightly larger Michelins than the original Goodyears I'd think you could go a bit lower but like that comment in the Goodyear literature said there would be little to gain.

actually I went with GOODYEAR G670 RV 275-70-22.5'S

THE FLEETWOOD placard says run 120 psi on the front with the 255-70-22.5's it came with... I think the reason isn't is much the actual weight up front (7000lbs) but the transfer weight with hard braking and the sway and porpoise problem with the short 208 wheel base...

Goodyear says to run the 255's at 80 psi with a 8380lb front weight... with a visual inspection you can see the side wall bulging way out and the appearance of a low tire pressure...

with a low tire pressure you get a false sense of a smooth ride, one that usally is try'n to compensate for poor suspension and components ...

with low pressure on a rv you get increased side wall flex, tire shake, and a huge increase of damaging the shinny the new aluminum rims...that and an increase in tire damage due to un repairable sidewall damage...


with low tire pressure you pick up side wall flex, shake and tire growth...


so to answer your question...I'm running the tire to start at 100 psi....
at this point they pass the visual inspection cold,,, the side walls look proper..
keep in mind that I have changed out the sachs shocks for the very best Bilstiens that are valved correct to the rv...


my RV rides good for an rv.. and great foer a 208'' wheelbase coach...


RV's only ride smooth on a smooth road..all of them period!!!!


next I will look at the air bags and see if there is anything to gain with adjustment.......I remember my discovery riding so horrible down the 15 freeway that the cabinette and tv came loose....


I remember having to modify the front air bag lever... but don't remember what I did..

[LVRVLUVR]

Another thing to add,...

the 255-70-22.5 is too small of a tire for the 8.25 rim...
with a visuall inspection you can see the rim is wider than the tire tread,,,

that means its at greater risk of rim damage due to pot holes and road hazards ..... now lower the pressure from the recommended 120 psi...
even greater risk and will multiply the damage

[LVRVLUVR]

Originally Posted by Waiter21

Ray, Yes, I understand the tables are for cold temperatures.

In your opinion, what is the maximum tire pressure?

tires are expected to get an amount of heat....that is engineered in to the tire specs...and pressure will rise... just to know you can record how much the pressure rises with abient temp....
there is no need to check tire pressure of a proper inflated cold tire... what you check for is heat...
when towing and driving rv's what I do is run down the road and at first leg stretch I walk the rig... I touch all the tires with the back side of my fingers... what I'm looking for is a hot tire... a hot tire is a proplem tire...

the heat will over inflate and blow the tire


the usual problem is low air pressue when cold ... or leaking pressure..
now you have a problem...you know it was at 100psi when you left...

now hot its at only 75.....so you add air and head to the tire store...

the next problem is over loaded trailer....all the tires are hot

[jadatis]

The AT-pressure of yours 125 psi is not the maximum pressure of the tire.
Tires are tested to can stand an absolute pressure of 2 to 3 times the AT-pressure .
So dont be afraid to go over the AT-pressure .
But be that sometimes for instance tires constructed for F-load can be set in the marked as G-load or worse H load.
then this 2 to 3 times higher pressure is going from F-load so 95 psi = 190 to 285 psi . enaugh thoug for H load ( AT 120psi) to be filled at 30 degrees F at 1.4 timmes AT pressure so 168 psi to rise by temperature rising to 212 degr F ( boiling point of water) , but to the edges already .

[LVRVLUVR]

Originally Posted by Waiter21

NO, that is not correct - The weights are for each tire, not each axle.

Please refer to the table, find your tire, then you can look at the pressure vs load.

According to the table, at 85psi cold, the maximum weight your tire will support is:

Front tire - 4920lbs .. Front axle = (4920 * 2 = 9,840lbs)

Dully tire - 4590lbs .. Rear axle = (4590 * 4 = 18,360lbs)

The pressures from the table are Minimum pressure for that load. You can put in higher pressure if you wish, I would not exceed 120psi for that particular tire.

You must also consider "What is the pressure when the tire is hot?. That pressure should not exceed 120psi (the max for your tire)

your calculated estimate was far better than my wild guess...

I ended up at 85psi all four, thanks for posting

[hackman]

I notice several posters making comments regarding maximum tire pressure. It should be remembered that the maximum tire pressure allowed probably exceeds the maximum pressure rating on your wheel rims. In my case the Alcoa rims are rated for 120 psi cold.

I think there are few coaches requiring pressures this high.