Tire pressure specs - discrepancy between Fleetwood and Michelin

[RMD3819]

Originally Posted by Tireman9

Have you checked my blog posts on weight & inflation?

BUT quick basic answer.
1. You need to lower the weight on the front. This can be done by removing stuff from the RV and/or adjusting the Tag support. I will defer to other owners of your model RV on how to adjust the tag.

2. take the axle figures and calculate 53% (This is an approximation till you can learn the actual corner weights) Use the 53% figure when consulting Load/Inflation tables to learn the minimum inflation you need

3. Tables will show "Single" (Front or Tag) line and a "Dual" (drive) line of loads with corresponding minimum inflation.

4. Add 10% to the minimum infl in #3 above and that is what I would suggest you run for morning Cold Inflation Pressure CIP

5 Run a TPMS that is set to alert at no lower than 95% of the min infl in #3 above. High pressure warning can be 120% to 125% of pressure in #4 above. High Temp warning can be about 160°F (70°C)

6 review my RV Tire Safety blog

7 Go have fun

I read your blog. Very interesting.

Doing the math:

Front axle at 53% comes out to 7441 which is between the 7300 (110psi) and 7570 (115psi). Rounding down (or should I round up?) 110psi + 10%=121psi

Rear axle at 53% is 13790 which is between 13420 (115psi) and 13880 (120psi). Rounding up this time 120psi + 10%=132.

Both of these are above the 120psi max on the sidewall. Is that OK?

Also-what about the tag axle psi?

Appreciate the help.

[Tireman9]

Originally Posted by RMD3819

I read your blog. Very interesting.

Doing the math:

Front axle at 53% comes out to 7441 which is between the 7300 (110psi) and 7570 (115psi). Rounding down (or should I round up?) 110psi + 10%=121psi

Rear axle at 53% is 13790 which is between 13420 (115psi) and 13880 (120psi). Rounding up this time 120psi + 10%=132.

Both of these are above the 120psi max on the sidewall. Is that OK?

Also-what about the tag axle psi?

Appreciate the help.

When using tables select the pressure that will carry equal or more than the measured load.
Front 120 is fine. What is your front GAWR?

Sounds like you are heavy in the rear. I would not run more than 120 psi. I also suggest your measured load be closer to 85% of the tire max than 100% of the tire max. What is rear GAWR

Tag is calculated like a single (front)

Tag adjustment can make loading more complex as the adjustment of the tag axle load shifts weight front to rear. What is TAG GAWR?


My 53% is an estimate. Since you are at or above suggested loads using 53% you really need to get actual axle end weights. Check HERE

[Sawsaw123]

Originally Posted by 4x4van

That is an incorrect statement. The number on the tire sidewall (110psi) is the pressure required for the maximum weight that the tire can carry, regardless of what vehicle the tire is installed on. The number stipulated by Fleetwood on the placard (90psi) is the pressure required for YOUR RV at IT'S maximum weight. Your coach has a front GAWR of 8,000# and a rear GAWR of 15,000#, both of which correspond to 90psi per Michelin's inflation/load table. Again, that 90psi is for those tires, installed on your RV, loaded to it's maximum weight; if you weigh less, then you may be able to safely run even lower pressures.

At 110psi (what you are reading on the sidewall), your tires will support 9,350# front and 17,640# rear; way over what your RV should ever weigh fully loaded.

I agree 100%. Best explanation of how to properly explain tire pressure.

[RMD3819]

Originally Posted by Tireman9

When using tables select the pressure that will carry equal or more than the measured load.
Front 120 is fine. What is your front GAWR?

Sounds like you are heavy in the rear. I would not run more than 120 psi. I also suggest your measured load be closer to 85% of the tire max than 100% of the tire max. What is rear GAWR

Tag is calculated like a single (front)

Tag adjustment can make loading more complex as the adjustment of the tag axle load shifts weight front to rear. What is TAG GAWR?


My 53% is an estimate. Since you are at or above suggested loads using 53% you really need to get actual axle end weights. Check HERE

Front 14700
Rear 21000
Tag 10000

I will be at the Passport America rally, the Newmar factory, and Freightliner during June/July. I am hoping one of those will be able to do corner weights.

[Tireman9]

Originally Posted by RMD3819

Front 14700
Rear 21000
Tag 10000

I will be at the Passport America rally, the Newmar factory, and Freightliner during June/July. I am hoping one of those will be able to do corner weights.

RVSEF will be in Indy in mid July. You might contact them

[RMD3819]

Originally Posted by Tireman9

RVSEF will be in Indy in mid July. You might contact them

Thanks for the link. Until I can get corner weights...

So...you said 120 for the front.

What about the rear?

What about the tag?

[Busskipper]

Originally Posted by rguild

I have a 2015 Fleetwood Bounder 33C which I purchased last January. I am a full timer and already have 15,519 miles on it. I am concerned because I see tire wear on the outside of the tread and the pressure specs on my Michelin are 110 PSI while the specs stipulated by Fleetwood customer service are 90 PSI.



Can someone offer advice? At the rate I am getting outer tire wear, I will need replacements well before the expected tire life. I suspect I will also have avoided the tire warranty.

Pretty Simple on this one - Who Builds Tires? - You answered the question! Simple if the outside is wearing then the air is low - do all the math you want -

JMHO,

[FastEagle]

Originally Posted by rguild

I have a 2015 Fleetwood Bounder 33C which I purchased last January. I am a full timer and already have 15,519 miles on it. I am concerned because I see tire wear on the outside of the tread and the pressure specs on my Michelin are 110 PSI while the specs stipulated by Fleetwood customer service are 90 PSI.

As we know, under-inflation leads to the uneven tread wear on the outer sides. I had the opportunity to discuss this with a Goodyear shop manager who confided with me that the same situation occurred with the infamous Ford Explorer rollovers in the last decade. He said Ford's PSI specs were well below the specs recommended by Firestone whose tires Ford put on the Explorers.

He recommended I split the difference between 90 PSI and 110 PSI but cautioned it could cause problems with my insurer in the event of an accident.

I have contacted Fleetwood customer support about this and have been told I needed an alignment but the tire guy told be the problem was not alignment but under inflation.

Can someone offer advice? At the rate I am getting outer tire wear, I will need replacements well before the expected tire life. I suspect I will also have avoided the tire warranty.

Tire manufacturers do not set vehicle cold recommended (correct) inflation pressures. The vehicle manufacturer does. Whatever is recommended on your RVs tire placard is good as long as you are not overloaded or under inflated due to a miscalibrated tire gauge.

[Tireman9]

Originally Posted by RMD3819

Thanks for the link. Until I can get corner weights...

So...you said 120 for the front.

What about the rear?

What about the tag?

I am concerned about the numbers you are reporting. Are you under the GAWR for each axle?

In an earlier post you reported
Steer axle 14040
Drive axle 26020
Tag axle 3520
Gross weight 43580


Are you also under the GVWR? Normally GVWR is less than the sum of the individual axles.

Do you know how to adjust the TAG loading? You need to review the process with someone familiar with your brand coach and chassis. Changes in TAG axle settings will change both front and drive axle loading.

In my previous replies I said to not run more than 120 psi in the tires. I also said you can calculate the inflation on the tag the same way you do the fronts but until you get all the weights (axle and vehicle ) below the rating ( not just a couple pounds under but hundreds under) we are just arranging the deck chairs on the Titanic.

What are the tire pressure numbers on the certification label?

[RMD3819]

Originally Posted by Tireman9

I am concerned about the numbers you are reporting. Are you under the GAWR for each axle?

In an earlier post you reported
Steer axle 14040
Drive axle 26020
Tag axle 3520
Gross weight 43580


Are you also under the GVWR? Normally GVWR is less than the sum of the individual axles.

Do you know how to adjust the TAG loading? You need to review the process with someone familiar with your brand coach and chassis. Changes in TAG axle settings will change both front and drive axle loading.

In my previous replies I said to not run more than 120 psi in the tires. I also said you can calculate the inflation on the tag the same way you do the fronts but until you get all the weights (axle and vehicle ) below the rating ( not just a couple pounds under but hundreds under) we are just arranging the deck chairs on the Titanic.

What are the tire pressure numbers on the certification label?

The "tag" number above is actually the trailer (toad) weight so separating that number out I am at 40060 which is below the 44000 GVWR.

I understand to use the tag as a single axle but I don't know what the tag weighs nor how to calculate it out from the drive axle weight.

The numbers on the manufacturers label are 120 for the front and 85 for the rear and tag.

The numbers on the Freightliner label are 120 all around.

[Crasher]

Originally Posted by RMD3819

The "tag" number above is actually the trailer (toad) weight so separating that number out I am at 40060 which is below the 44000 GVWR.

I understand to use the tag as a single axle but I don't know what the tag weighs nor how to calculate it out from the drive axle weight.

The numbers on the manufacturers label are 120 for the front and 85 for the rear and tag.

The numbers on the Freightliner label are 120 all around.

The first thing you need to do is to go to the scale without the toad. Drive onto the scale so that each axle is on a separate platform. This will tell you what each one weighs. Your previous weight with the tag and drive axle on the same platform is of no use to you. You need to separate them and then come back for help.

[manderson2228]

I've read all this, and while a lot has gone into setting the right pressures and such which i certainly agree with. For my money there is literally not a single reason why you shouldn't go and get it aligned either way. A good alignment to me is the place to start, then tune your pressures and see how it runs then.

[Tireman9]

Originally Posted by RMD3819

The "tag" number above is actually the trailer (toad) weight so separating that number out I am at 40060 which is below the 44000 GVWR.

I understand to use the tag as a single axle but I don't know what the tag weighs nor how to calculate it out from the drive axle weight.

The numbers on the manufacturers label are 120 for the front and 85 for the rear and tag.

The numbers on the Freightliner label are 120 all around.

Need to get the terminology straight.

A toad with 4 down places almost zero additional load on the RV tires so should not be in the conversation.

Freightliner info does not apply as that was a chassis only and not the RV.

You have 3 axles under the RV Front "intermediate" or drive and rear or Tag

The drive axle has 2 tires on each end so that means you use the "dual" line of the inflation table

The front and tag (rear) have one tire on each end so you use "single" line in the table.

When on the scales you need to stop so the drive and tag axles are on different platforms.

We need to know the scale weights for Front, drive and tag axle of the RV as separate numbers. We do not need to know and do not want to include the toad weight or numbers. Then we can start over.

[RMD3819]

Originally Posted by Tireman9

Need to get the terminology straight.

A toad with 4 down places almost zero additional load on the RV tires so should not be in the conversation.

Freightliner info does not apply as that was a chassis only and not the RV.

You have 3 axles under the RV Front "intermediate" or drive and rear or Tag

The drive axle has 2 tires on each end so that means you use the "dual" line of the inflation table

The front and tag (rear) have one tire on each end so you use "single" line in the table.

When on the scales you need to stop so the drive and tag axles are on different platforms.

We need to know the scale weights for Front, drive and tag axle of the RV as separate numbers. We do not need to know and do not want to include the toad weight or numbers. Then we can start over.

OK....starting over I did a weigh without the toad and with the axles on separate platforms:

Steer 14140
Drive 17640
Tag 8520
Gross 40300

The only glitch is my wife was not in the coach at the time-she was spotting me on the scale. I assume just add her weight to the front axle. The 14140 is 140# over the axle limit so that will just make that number worse.

I don't know of a way to adjust the tag axle as you have mentioned to help compensate for this.

Following your formula of 53% of the weight plus 10% I come up with the following:

Front 8243 which is overweight I know but 120psi cold
Rear 10285 85psi cold
Tag 4966 75psi cold

Tires are Michelin 305 70 22.5
Axle ratings:
Front 14000
Rear 20000
Tag 10000
GVWR 44000

Is this correct?