MH tire PSI conflicting info

[ezgoin]

The Yellow capacities sticker in my 31' MH lists cold Max PSI at 85 lbs. for all tires, but the Ford chasis sticker lists max PSI at 82 lbs., at the same load capacities. I know it's not much difference, but I was considering lowering the PSI slightly as I'm a little under max GVWR. Which numbers should I use? Any suggestions?

Thanks for all your help.

[Tireman9]

Cmore12 wrote:
After reading here, I went to the Tiffin forum. There is a 3-page EXTENSIVE post/responses set on this. Here's a "short?" bullet point summary:
1. 4-corner weighing is the best info. Done at rallies, etc. Must be level.
2. Weighing left side/right side & do the math at a CAT scale is NOT OK.
3. If just weighing axles, add 5% weight, then consult the manufacturer's chart and add 5 psi. This is conservative enough to make up for unbalanced sides.
4. Each axle MUST have same pressure side to side. Use heaviest.
5. This changes my numbers to 81 psi front & 86 psi rear. That's 25+ BELOW what the dealer put in.
6. Over pressure a bit is OK.
7. Under pressure is dangerous.
Smarter folks than me have beat this to death, but this is in line with the consensus of posts here.
Cheers,
Me, my Honey, & two dogs cuter than yours

comments and advice deleted by author. good luck and safe travels.

[Tireman9]

comments and advice deleted by author. good luck and safe travels..

[Tireman9]

ezgoin wrote:
The Yellow capacities sticker in my 31' MH lists cold Max PSI at 85 lbs. for all tires, but the Ford chasis sticker lists max PSI at 82 lbs., at the same load capacities. I know it's not much difference, but I was considering lowering the PSI slightly as I'm a little under max GVWR. Which numbers should I use? Any suggestions?

Thanks for all your help.

comments and advice deleted by author. good luck and safe travels.

[Tireman9]

Executive wrote:
There should be a sticky that doesn't allow one to ask these questions until their rig is weighed...I cannot believe how many people do not know the weights of their equipment.

PSI is based on axle weights...period...with a small buffer if you wish. It's a fact that almost ALL blowouts are the result of underinflation of the tires. All tire manufacturers advise to use their tire inflation tables NOT what's printed on the sidewall.....it's certainly not rocket science....weigh your rig, consult the inflation tables, air up the tires and enjoy the trip.....:).....Dennis

[Cmore12]

After reading here, I went to the Tiffin forum. There is a 3-page EXTENSIVE post/responses set on this. Here's a "short?" bullet point summary:
1. 4-corner weighing is the best info. Done at rallies, etc. Must be level.
2. Weighing left side/right side & do the math at a CAT scale is NOT OK.
3. If just weighing axles, add 5% weight, then consult the manufacturer's chart and add 5 psi. This is conservative enough to make up for unbalanced sides.
4. Each axle MUST have same pressure side to side. Use heaviest.
5. This changes my numbers to 81 psi front & 86 psi rear. That's 25+ BELOW what the dealer put in.
6. Over pressure a bit is OK.
7. Under pressure is dangerous.
Smarter folks than me have beat this to death, but this is in line with the consensus of posts here.
Cheers,
Me, my Honey, & two dogs cuter than yours

[Oldme]

Weight the coach.
Contact Customer Service for your tire manufacturer.

The tire manufacturer guarantee the tires and certify
them for the various weights NOT the MH manufacturer.

The TIRE Manufacturer will give you proper PSI based
on your LOADED weight.

[rollingslow]

wa8yxm wrote:
FORD likes to run tires low so as to give a softer ride, Never mind that this leads to sidewall failure (Remember the Ford Roll-a-matic,er, explorer fiasco that Ford blamed Firestone for... Well it was FORD's fault). so I'd go with the tire maker's suggestions.

And second, Get the thing weighed, 4 corner weights (Instructions for that all over every forum) and inflate to the tire maker's chart, optionally plus 5 PSI, This is the proper inflation for maximum tire life and control.. Inflating to the max is almost never the proper pressure.

The ford roll-a-matic.

Ford said to run 'em 5 PSI low.. So people did, and since a NEW TIRE does not leak (much) They never checked them,, The technician at the last oil change was in a hurry so he did not either, Thus instead of being 5 PSI low, they are closer to 5 PSI.

Now driving down the road they hit one of our nations' most popular freeway features (Voice of doom mode on) THE POT HOLE (Voice of doom mode cancel) and when they hit the far edge, what happened,,, The rim slided that sidewall like it was hot butter Cause there was no pressure to protect it.

So what did Mr. Yuppie who has never driven a truck in his life do? Stand on the brakes with both feet of course.. Whats #1 on the list of thigns to NEVER do when you get a flat tire.. You guessed it, Stand on the brakes with both feet.

What's #2..... Roll over and die.

So it's fords fault that people dont check there tires. I dont agree thats your job if you drive it

[wolfe10]

Cmore12 wrote:
The local dealer says they always set the max listed on the sidewall (110psi). I weighed & consulted the Michelin chart. 71psi front & 76 rear. That's a HUGE difference. It's time to check a different reliable source.

I would consider Michelin a good, reliable source for inflation information for their tires.

BTW, the correct way to read the inflation chart is to use the heavier wheel position on an axle to determine the correct MINIMUM PSI for all tires on that axle. I say minimum, because if it weighs more, the chart calls for more PSI.

Many of us add 5 PSI to the chart's "minimum PSI for a given weight" as a small fudge factor.

[Cmore12]

The local dealer says they always set the max listed on the sidewall (110psi). I weighed & consulted the Michelin chart. 71psi front & 76 rear. That's a HUGE difference. It's time to check a different reliable source.

[frankdamp]

"Max" pressure is what the MH manufacturers and the tire manufacturers consider the highest safe pressure for the installed tires. It bears no correlation to what is a good working pressure based on the load they're carrying.

Load your rig like you're going on a trip and go to the nearest truck scale. Weigh the front with the back wheels off the scale, then do the back wheels with the front ones off the scale. Once you have those numbers, divide by two for the front wheels and by four for the duallies. Then look up the tire manufacturer's recommended pressure for those loads for each tire. Those are the pressures you should use, but +/- 10% won't hurt much. In most rigs, side-to-side differences won't be critical, but if you really want to get scientific, weigh the right side and the left side with the opposite side off the scale pad.

Over-inflation for the load the tire is carrying will result in more wear in the middle of the tread than at the sides. Under-inflation produces the opposite. There's lots of leeway in this equation, so don't "get your knickers in a twist" as we Brits say.

[wildmanbaker]

Weighing the 4 corners is not an easy task. How you are centered on the scales has a large effect on the weights you will get. Consult with the weightmaster as to where to position the MH for the most accurate weights. Weight your MH on a platform scale to get the actual weight. Weight the front axle, rear axle, and each side, and each tire location. Guess what, They most likely will not equal the total weight of the MH. Use the heavy side of the axles to determine the weight. Your side to side weight will most likely not be equal either. After all the weighing, and determining the pressure for the weights, which was less than the pressure specified by Fleetwood, I went back to what Fleetwood recommended for better handling and cooler tire temps.

[wa8yxm]

EDM, even if the tire was made specifically to fit a Belchfire 37 footer... (Made up model) they can not predict how many pounds of food, cloths and even PEOPLE will be inside the rig as it goes bouncing down the highway.. So they can not predict the proper tire pressure.

THUS, you MUST put it on a scale and get your 4 corner weights (Procedure elswhere in forum, about a thousand elsewheres) that is the ONLY way to figure out the proper PSI.

And apologies to the cartoonist who has his characters, from time to time, visiting Belchfire Motors for his new car.

[edm3rd]

As far as I know, almost no tires are manufactured for a single vehicle - most all go different chassis makes, different types, ie trucks, vans, RV's, trailers and others. Just another reason the sticker/label from the company that completed the vehicle is much more specific than what the tire manufacturer shows as maximum.

But the bottom line is the vehicle needs to be weighed, and appropriate pressure based on load.

[DanTheRVMan]

Executive wrote:
There should be a sticky that doesn't allow one to ask these questions until their rig is weighed...I cannot believe how many people do not know the weights of their equipment.

PSI is based on axle weights...period...with a small buffer if you wish. It's a fact that almost ALL blowouts are the result of underinflation of the tires. All tire manufacturers advise to use their tire inflation tables NOT what's printed on the sidewall.....it's certainly not rocket science....weigh your rig, consult the inflation tables, air up the tires and enjoy the trip.....:).....Dennis

I agree, people need to set their pressure based on axle weights

My guess is
25+% do not know the psi in their tires
25+% use a psi they heard some one with a similar MH uses for their tires
45+% use axle weights
<5% use 4 corner weights

Asking people to use 4 corner weights is as effective as asking people have bigfoot set the psi in their MH

Tires do not fail because people set their psi based on axle weights.