Michelin Agilis confusion??

[dznf0g]

Originally Posted by Al and Missy

I took the phrase "add 10% margin" to mean ADD 10% to my weights" not SUBTRACT 10% from the table weight.

But this is probably arranging deck chairs - pick the one that yields the most pressure. The difference probably won't change the ride much.

That's what I thought as well. The question just popped as I was noodling all this.

[Wazbro]

Originally Posted by dznf0g

AWhen you add 10% margin for using non-st tires on a trailer, do you add 10% to your actual weight and use the corresponding chart psi......or do you de-rate the chart weight number by 10%? They are different numbers.

Edit: sendel t02 16x6 wheels are 110psi max wheels.

I thought that 10% was just for using P rated tires not LT, I would need to find it to be sure.

Still the carts are minimum pressures to use, so adding 10 psi shouldn't be a problem, check after a few thousand miles to see how everything is doing.

[dznf0g]

Originally Posted by Wazbro

I thought that 10% was just for using P rated tires not LT, I would need to find it to be sure.

Still the carts are minimum pressures to use, so adding 10 psi shouldn't be a problem, check after a few thousand miles to see how everything is doing.

I have no clue how to locate the thread containing those recommendations..there have been so many. I recall the 10% was for anything other than an ST tire. I also recall a discussion that another 5% was to be added for unequal loading of the 4 tires in at least one thread.
Interestingly enough, adding 15% gets near the 10psi higher number on the chart.

Hmmmm, where are the tire engineers when you need them?

[CapriRacer]

A lot to unpack. Here goes:

1) The load table is the load table. If you want to know what the relationship is between inflation pressure and max load, look at the load table.

In this case, the load table says 2680# at 80 psi.

That means the OP should do what he did before - unless this is the first time using that size (as in he recently went from 15" to 16".) I can't tell if that is the case, but if it is, I would start with the same pressure used by the 15".

2) It is unfortunate, but Michelin has done what a few other tire manufacturers have done - and that is confuse the max pressure with the rated pressure. in this case 80 psi is the rated pressure (the pressure where the load carrying capacity maxes out), and 90 psi is the max pressure. The fact that they say "Max load 2680# at 90 psi" is misleading. More correctly they should have said "Max Load 2680# at 80 psi, Max pressure 90 psi". I wonder what it says on the sidewall.

So, OP, there you have it. There isn't a load table with 90 psi, because it's supposed to be 2680# at 80 psi, and you can use up to 90 psi with no change in max load.

Now to the other question in this thread: the 10% factor.

That factor only applies to P type tires used in light truck and trailer usage. It does not apply to LT and ST tires because they both have that factored in per the load tables.

Just be aware that there are other factors that are supposed to be applied - such as a 10% RVIA factor applied to the trailer GAWR (Gross Axle Weight Rating), when selecting a tire size/inflation pressure.

Again, I advise the OP to use the same pressure as before - regardless of whether the previous tire is 15" or 16". In the case of a 15" to 16" switchover, that takes advantage of the additional load carrying capacity obtained by the larger tires, but maintains the ride quality.

[dznf0g]

Originally Posted by CapriRacer

A lot to unpack. Here goes:

1) The load table is the load table. If you want to know what the relationship is between inflation pressure and max load, look at the load table.

In this case, the load table says 2680# at 80 psi.

That means the OP should do what he did before - unless this is the first time using that size (as in he recently went from 15" to 16".) I can't tell if that is the case, but if it is, I would start with the same pressure used by the 15".

2) It is unfortunate, but Michelin has done what a few other tire manufacturers have done - and that is confuse the max pressure with the rated pressure. in this case 80 psi is the rated pressure (the pressure where the load carrying capacity maxes out), and 90 psi is the max pressure. The fact that they say "Max load 2680# at 90 psi" is misleading. More correctly they should have said "Max Load 2680# at 80 psi, Max pressure 90 psi". I wonder what it says on the sidewall.

So, OP, there you have it. There isn't a load table with 90 psi, because it's supposed to be 2680# at 80 psi, and you can use up to 90 psi with no change in max load.

Now to the other question in this thread: the 10% factor.

That factor only applies to P type tires used in light truck and trailer usage. It does not apply to LT and ST tires because they both have that factored in per the load tables.

Just be aware that there are other factors that are supposed to be applied - such as a 10% RVIA factor applied to the trailer GAWR (Gross Axle Weight Rating), when selecting a tire size/inflation pressure.

Again, I advise the OP to use the same pressure as before - regardless of whether the previous tire is 15" or 16". In the case of a 15" to 16" switchover, that takes advantage of the additional load carrying capacity obtained by the larger tires, but maintains the ride quality.

Thanks for coming in!

Yes, I have been using the same size LT tires (michelin LT225/75R16) since 2011. Always run at 80psi. This is my 3rd set. The sidewall of that size Agilis says 2680 @ 90psi. Pic posted upthread. That is where my confusion came in...that and the odd table printing with no footnotes.

So can you humor me with some math?

I know my total 2 axle/4 tire load is 8420#, fully loaded and full fresh water and water heater full. (worst case scenario)

So, each tire is 2105# (except I know that they are probably not equal to one another). Can you walk through the chart and tell me where I land? I think I am at 80psi, but I have been adding 10% and then another 15% to my actual tire load. Is that correct methodology?

[CapriRacer]

Originally Posted by dznf0g

Thanks for coming in!

Yes, I have been using the same size LT tires (michelin LT225/75R16) since 2011. Always run at 80psi. This is my 3rd set. The sidewall of that size Agilis says 2680 @ 90psi. Pic posted upthread. That is where my confusion came in...that and the odd table printing with no footnotes.

So can you humor me with some math?

I know my total 2 axle/4 tire load is 8420#, fully loaded and full fresh water and water heater full. (worst case scenario)

So, each tire is 2105# (except I know that they are probably not equal to one another). Can you walk through the chart and tell me where I land? I think I am at 80psi, but I have been adding 10% and then another 15% to my actual tire load. Is that correct methodology?

Yes, I think that's right.

[dznf0g]

Originally Posted by CapriRacer

Yes, I think that's right.

Great, thanks! I have re-read your Tire tech pages (it had been years since I really studied it hard).

I believe I have landed here:

Full water came out to 78psi....round up to nearest 5psi = 80psi

Half tank water came out to 75psi

No water came out to 72psi...round up to nearest 5psi = 75psi

So my full loaded trailer with variable water loads would require really only one adjustment...from 75psi to 80 psi on the rare occasions when I travel with a full tank. I predominantly travel with less than 1/2 tank, and empty or near empty waste tanks.

[JetstreamAS]

Originally Posted by dznf0g

Great, thanks! I have re-read your Tire tech pages (it had been years since I really studied it hard).

I believe I have landed here:

Full water came out to 78psi....round up to nearest 5psi = 80psi

Half tank water came out to 75psi

No water came out to 72psi...round up to nearest 5psi = 75psi

So my full loaded trailer with variable water loads would require really only one adjustment...from 75psi to 80 psi on the rare occasions when I travel with a full tank. I predominantly travel with less than 1/2 tank, and empty or near empty waste tanks.

Rich-

If your max weight is 2105# per wheel before you add 10% for a max per wheel to get to 2316#, why would you run at 75 or 80 per the chart? Because of the additional 15% added on top?

[dznf0g]

Originally Posted by JetstreamAS

Rich-

If your max weight is 2105# per wheel before you add 10% for a max per wheel to get to 2316#, why would you run at 75 or 80 per the chart? Because of the additional 15% added on top?

Yes, go here and scroll down....

http://www.barrystiretech.com/sttires.html

"If you only know the total weight on the tires (but minus the hitch weight):"

That's all I know from cat scales. I could weight each axle independently and go to: (on the same page)

"If you only know the axles loads or only know the weight side to side:"

Or, if I were a rich man and bought race car scales, I could go to: (on the same page)

"Determine the max tire load:" and follow Barry's link to page 45 of that document. In that case, the 10% is dropped.

AS I UNDERSTAND IT ALL.??

So for me,

Axle loads of 8421/4 = 2105#
X10% = 210#
X15% = 316#
Added together is 2631# which equals 78ish psi = round up to nearest 5# = 80psi

That's my heaviest, worst case scenario weight.

[gypsydad]

How many times this topic has been discussed over the years, and still seems like it is rocket science sometimes when I read the details here. I remember when Michelin stopped making the 15" LT tires and the Marathons were replaced with the GYE's, and this "confusion" over the meaning of Max PSI (least for me was still some confusion), I called both JC and the folks at Michelin; also talked with the GY folks; asked about the "Max"question. You see, many folks were/are still running at Max PSI, including me back in the day. Popped rivets, broken hinges, broken closet door hinge, shower door broken hinge and laying on the floor, etc. were effects I experienced early on while running at Max PSI with my 25's. I was told by the folks at AS and also Michelin techs I called on this topic; both said that Max was a "not to exceed" number. The AS guys told me this topic/question comes up all the time from TT customers with not just AS. They put the sticker on the side of the TT's and vehicles also. Most folks don't know what their AS weighs, so think of it as a "don't exceed" Both folks I spoke with recommended I follow the mfg. chart for "Max" number; not as a recommended best psi. best performance for weight of my AS loaded. That was in the ~40-45PSI range as I recall. I was also told this would not affect tread wear. I started running at 45PSI cold after that but I thought it was too low and eventually moved up to 50, then to 55PSI...now I run 58-60PSI cold with the GYE's on the 28FC. No issues with interior, nor signs of frame/body separation after 6 years and 55K miles, and now on my second set of GYE's.

I appreciate the experts input here for sure....interesting to re-read this topic each year or so and learn more...

[dznf0g]

Originally Posted by gypsydad

How many times this topic has been discussed over the years, and still seems like it is rocket science sometimes when I read the details here. I remember when Michelin stopped making the 15" LT tires and the Marathons were replaced with the GYE's, and this "confusion" over the meaning of Max PSI (least for me was still some confusion), I called both JC and the folks at Michelin; also talked with the GY folks; asked about the "Max"question. You see, many folks were/are still running at Max PSI, including me back in the day. Popped rivets, broken hinges, broken closet door hinge, shower door broken hinge and laying on the floor, etc. were effects I experienced early on while running at Max PSI with my 25's. I was told by the folks at AS and also Michelin techs I called on this topic; both said that Max was a "not to exceed" number. The AS guys told me this topic/question comes up all the time from TT customers with not just AS. They put the sticker on the side of the TT's and vehicles also. Most folks don't know what their AS weighs, so think of it as a "don't exceed" Both folks I spoke with recommended I follow the mfg. chart for "Max" number; not as a recommended best psi. best performance for weight of my AS loaded. That was in the ~40-45PSI range as I recall. I was also told this would not affect tread wear. I started running at 45PSI cold after that but I thought it was too low and eventually moved up to 50, then to 55PSI...now I run 58-60PSI cold with the GYE's on the 28FC. No issues with interior, nor signs of frame/body separation after 6 years and 55K miles, and now on my second set of GYE's.

I appreciate the experts input here for sure....interesting to re-read this topic each year or so and learn more...

Yeah, I hear ya, but the subject of this thread arose from the odd chart and the 2 different numbers (the 2680# @ 80psi vs the far right "maximum load and pressure on sidewall" numbers of 2680# at 90psi)

I don't believe anything has changed over quite a few years relative to Barry's methodology for determining proper trailer pressures.
So the way I read/infer the strange chart entries for ONLY(???) that LT275/75R16 tire is Michelin, for some reason chose to....um....clarify....maybe.... the margins laid out by Barry and others relative to trailer use???

So the way I see it, the max physical load (weight) for the tire is 2680#. But if you are going to run those tires on an RV/Trailer there needs to be some "margin" (pressure) added for their service type.

My (inferred) calculations say that 90psi wouldn't be enough to run an actual 2680# weight, based upon the margins prescribed by Barry. It would be time to look at a larger size or the c-metric tire.

So the additional PSI (to 90#) is to account for assigned margins, not physical load.

At least that is my deduction at this point.

[CapriRacer]

Originally Posted by dznf0g

Yeah, I hear ya, but the subject of this thread arose from the odd chart and the 2 different numbers (the 2680# @ 80psi vs the far right "maximum load and pressure on sidewall" numbers of 2680# at 90psi)

I don't believe anything has changed over quite a few years relative to Barry's methodology for determining proper trailer pressures.
So the way I read/infer the strange chart entries for ONLY(???) that LT275/75R16 tire is Michelin, for some reason chose to....um....clarify....maybe.... the margins laid out by Barry and others relative to trailer use???

So the way I see it, the max physical load (weight) for the tire is 2680#. But if you are going to run those tires on an RV/Trailer there needs to be some "margin" (pressure) added for their service type.

My (inferred) calculations say that 90psi wouldn't be enough to run an actual 2680# weight, based upon the margins prescribed by Barry. It would be time to look at a larger size or the c-metric tire.

So the additional PSI (to 90#) is to account for assigned margins, not physical load.

At least that is my deduction at this point.

I suspect you are asking why did Michelin use 90 psi for an 80 psi tire.

Michelin is the only one I know who is doing this - and they aren't doing this consistently. So you'll have to ask the guy who actually made that decision.

But I can supply a rationale:

If you go to the source of the load table - The Tire and Rim Association's yearbook - there is a supplemental note that in some circumstances, using +10 psi is permitted.

[dznf0g]

Originally Posted by CapriRacer

I suspect you are asking why did Michelin use 90 psi for an 80 psi tire.



Michelin is the only one I know who is doing this - and they aren't doing this consistently. So you'll have to ask the guy who actually made that decision.



But I can supply a rationale:



If you go to the source of the load table - The Tire and Rim Association's yearbook - there is a supplemental note that in some circumstances, using +10 psi is permitted.

Right, but if you can't exceed 2680# (in this case), and 80psi is prescribed at that weight, why would one increase the pressure except for a non-conventional application where additional margins are suggested, like a trailer application?

[ITSNO60]

Originally Posted by dznf0g

Right, but if you can't exceed 2680# (in this case), and 80psi is prescribed at that weight, why would one increase the pressure except for a non-conventional application where additional margins are suggested, like a trailer application?

Storage? I have seen recommendations for storage to inflate to max sidewall pressure.

[dznf0g]

Originally Posted by ITSNO60

Storage? I have seen recommendations for storage to inflate to max sidewall pressure.

I suppose that's possible...but only apply the sidewall higher pressure embossment and change the table for only this particular size Agilis?? Is it because of AS (and perhaps other manufacturers) recent offering of this tire and size as OEM??

Are AS 30' Classics (or 33') coming with this tire? If so, I would be curious what pressure is stamped on the trailer plate from AS and what GVWR?

I am suspecting they are 10,000GVWR, with 5,000 pound axles, and a 90psi recommendation.

Edit: In fact the AS brochure does say 10,000 GVWR and "Michelin LT225/75R16 Tires, Balanced". I assume Agilis, but it doesn't say.

[ITSNO60]

Originally Posted by dznf0g

I suppose that's possible...but only apply the sidewall higher pressure embossment and change the table for only this particular size Agilis?? Is it because of AS (and perhaps other manufacturers) recent offering of this tire and size as OEM??

Are AS 30' Classics (or 33') coming with this tire? If so, I would be curious what pressure is stamped on the trailer plate from AS and what GVWR?

I am suspecting they are 10,000GVWR, with 5,000 pound axles, and a 90psi recommendation.

Edit: In fact the AS brochure does say 10,000 GVWR and "Michelin LT225/75R16 Tires, Balanced". I assume Agilis, but it doesn't say.

That thought did cross my mind, they know the tire is used on trailers so the extra 10 lbs could go a long ways in reducing interply shear. (if one could tolerate the resulting ride)

[ROBERT CROSS]

I follow here...
The tires are inside 'Cloudsplitter' at 72-74 PSI. (running#)
Remember, if you're not sure...better a little high than not enough.

Bob
🇺🇸

It sez 80#...?

[CapriRacer]

Originally Posted by dznf0g

Right, but if you can't exceed 2680# (in this case), and 80psi is prescribed at that weight, why would one increase the pressure except for a non-conventional application where additional margins are suggested, like a trailer application?

OK, here's the part I left out that is part of The Tire and Rim Association's load table notes: That increasing the inflation pressure allows the user to operate at higher speeds. The note also talks about lowering the max load to accomplish the same thing. From a tire's perspective lowering the load and increasing the inflation pressure are the same thing.

So the increased pressure has nothing to do with trailers.

[dznf0g]

Originally Posted by CapriRacer

OK, here's the part I left out that is part of The Tire and Rim Association's load table notes: That increasing the inflation pressure allows the user to operate at higher speeds. The note also talks about lowering the max load to accomplish the same thing. From a tire's perspective lowering the load and increasing the inflation pressure are the same thing.



So the increased pressure has nothing to do with trailers.

Of course! That makes sense. Still weird that it's just that one size Agilis.

[dznf0g]

Although they do only show a single106mph speed rating (same as most all of the other sizes, and C-metric). And don't say if that's at 80 or 90psi. Not that mine will ever see anything north of 65mph, but it's still a mystery to me.