16" wheels/LT tires

[mefly2]

Originally Posted by m.hony

Most of the stuff on Airforums is pertinent/relevant. Hardly anything on Spacebook is.

Who are you calling relevant ...pertinent maybe, but relevant ... not to be anti social in this media event - but to be relevant, I will post again for the third time.

Originally Posted by mefly2

Good read ... what about torque variation when wiping dust off the threads (using an oily rag)- is that still considered dry torque value - as I asked before?
And, what is the variation in torque values if measured cold (as in it is freezing outside right now) vs checking in the summer at 75+ degrees F.?

As I said, torque values vary widely from completely "dry" / new or cleaned threads vs oxidized / lubricated threads ... as well as heated or cooled mating surfaces of the threads; hence the reason why we use penetrating oil (not on wheel studs) or heat to break loose stubborn bolts / nuts. Do any of you sage old social wizards know the answer to my above question???

[Ag&Au]

Originally Posted by mefly2

Who are you calling relevant ...pertinent maybe, but relevant ... not to be anti social in this media event - but to be relevant, I will post again for the third time.



As I said, torque values vary widely from completely "dry" / new or cleaned threads vs oxidized / lubricated threads ... as well as heated or cooled mating surfaces of the threads; hence the reason why we use penetrating oil (not on wheel studs) or heat to break loose stubborn bolts / nuts. Do any of you sage old social wizards know the answer to my above question???

I thought your question was rhetorical.
The answer is:
it depends on the humidity, day of the week, and whether or not you will be using nitrogen in your tires. (just saying you will use nitrogen adds 134.31 inch ounces(troy) to the necessary torque).

That is because just saying you put nitrogen in your tires does as much practical good as actually doing it.

Ken

[Ag&Au]

There is one facet to the torque issue that hasn't been touched on. The thing that damages the wheel is the amount of force with which the lug nut is pressing down on the wheel. This amount of force is dependent on the position of the nut on the bolt, not the force that is required to put the nut in that position(torque). The force required to place the nut in the desired position is dependent on many variables. However it is the force that we measure. This further illustrates the point that the values that anyone quotes are simply a starting point that must be frequently checked and adjusted as necessary. In addition there is usually (in a properly maintained system) a wide range between the minimum torque required to keep the wheels on the vehicle and maximum torque before damage is done.

The reason so many different values are being quoted is that they all lie withing the range of acceptable ones. It is not possible to pick one best value for all conditions.

Ken

[TinTin]

Perhaps an over-complication? Once one shape of lug nut will fit the lug seat on the wheel correctly, and this is what the torque specs will be for.


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[TinTin]

Once = Only


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[ROBERTSUNRUS]

Hi, just use what I used to call Chevrolet Torque; Tighten until they snap and back off a quarter turn.

[Ag&Au]

Originally Posted by ROBERTSUNRUS

Hi, just use what I used to call Chevrolet Torque; Tighten until they snap and back off a quarter turn.

By snap, do mean the bolts break?

If you mean the snap noise a preset torque wrench makes when it reaches the setting, that's what I do, except I don't back it off. Have I been living on the edge all this time?

Ken

[ROBERTSUNRUS]

Originally Posted by Ag&Au

By snap, do mean the bolts break?

If you mean the snap noise a preset torque wrench makes when it reaches the setting, that's what I do, except I don't back it off. Have I been living on the edge all this time?

Ken

Hi, yes Ken; At the time Chevy used smaller bolts for everything than were used by Ford. It was very common to see broken carburetor studs and lug studs Etc. on Chevys back then. They were usually so tight that they would break while trying to loosen them. Hence the phrase, "Tighten them until they snap and back off a quarter turn."

[Chevrolet Torque]

[Gene]

Full disclosure—Bob worked for a Ford dealer in a past life.

TinTin—interesting point about the shape of lug nuts and the seat in the wheel. But I'm not sure it isn't "conventional wisdom". It seems like it could be true, but is there any proof of that? As long as the nut holds the wheel securely, seems like the torque could be the same. I realize some lug nuts fit part way into the hole and others have a lip that presses on the wheel, not inside the hole. Assuming that the nut and lug threads engage as much, torque should not change.

Gene

[BoldAdventure]

I saw awhile ago Switz mention that he ran Michelin LTX M/S2 - p235 75R15 XL on his 25fter because the GVWR was 7300lbs and that by the numbers 2183 per tire (not derated) they where more than adequate and not overkill as he mentioned he wouldn't run put 16's on the 25fter.

We have a 27fter GVWR 7500lbs and I keep wondering while this debate rages why I would need more weight rating than the 8732lbs of rating I'd have with just the 15's on my existing rims and some centramatics?

It would certainly be more cost effective.

I'm all over on making my mind up about this.

PS: I totally get stiffer side walls. I'm an offroader after all.

[blkmagikca]

Originally Posted by BoldAdventure

I saw awhile ago Switz mention that he ran Michelin LTX M/S2 - p235 75R15 XL on his 25fter because the GVWR was 7300lbs and that by the numbers 2183 per tire (not derated) they where more than adequate and not overkill as he mentioned he wouldn't run put 16's on the 25fter.

We have a 27fter GVWR 7500lbs and I keep wondering while this debate rages why I would need more weight rating than the 8732lbs of rating I'd have with just the 15's on my existing rims and some centramatics?

It would certainly be more cost effective.

I'm all over on making my mind up about this.

PS: I totally get stiffer side walls. I'm an offroader after all.

Travel isn't always ideal, so having a larger margin for safety isn't necessarily more costly once you factor in the probability of a tire failure. This doesn't mean that you WILL have a failure, it just means that there is a percentage of probability of one occurring.

We have a 32-ft Excella and in the 3+ years we've had it I have had several tire failures. I never chintz-ed on tires, so the issue became one of type, namely ST vs LT tires. Just to let you know, the cost of a blowout is not cheap, as there is usually some damage to the trailer; in my case it was just some of the sheet metal in the wheel well and the trim.

The GVWR of my trailer was 8,000 lbs (2 x 4,000-lb axles). When the time came this summer to change the axles, I opted for 4,500 lb ones, thereby increasing the capacity (GVWR) to 9,000 lbs - I did this as a margin for safety. At the same time I changed over to 16-inch wheels and Michelin LTX225/75R16(E) tires - that's load range E with a tire pressure of 80-psi.

This winter while I am in Arizona, I'm going to put my rig through the SmartWeigh program. See SmartWeigh_Default If there is any deficiency in my setup, I want to find it and correct it.

[Ag&Au]

I'm not going to try to figure out all the numbers you guys are using. However just want to be sure you know that a user on these forums "Capriracer" who is a tire engineer and seems to know what he is talking about has said that LT tires used in a trailer application should have their load ratings decreased by 15%. Perhaps that is in the numbers you are using. In that case never mind?

Ken

[SteveSueMac]

Bold - you'd have 7,936 with those Michelins because using a P rated tire on a trailer requires you to derate the load capacity by 10%.

I use them on my 27FB which loaded for camping on the scales sees 5800# on the trailer axles. That's literally more than a ton of headroom on the de-rated capacity of the tires.

Good luck!

[Andrew T]

We have installed the 15" Michelins on hundreds of Airstreams with virtually zero failures. Many of these are 30' models including older Classics with axle weights of 7500 pounds. Even at those weight ranges the tires run cool and are completely reliable.

The big advantage with them is that they are much easier on the Airstream and the items you carry inside it.

Andrew T

[sb55]

Andrew, Which specific Michelin tires would you install on a 2004 25' Safari SS? Thanks for you reply.

[CapriRacer]

Originally Posted by Ag&Au

I'm not going to try to figure out all the numbers you guys are using. However just want to be sure you know that a user on these forums "CapriRacer" who is a tire engineer and seems to know what he is talking about has said that LT tires used in a trailer application should have their load ratings decreased by 15%. Perhaps that is in the numbers you are using. In that case never mind?

Ken

Ah ..... Mmmm ..... Not exactly.

I think tires should never be loaded to more than 85% of their rated capacity (which includes the adjustment if you are using a lower inflation pressure.)

This applies to ALL tires, not just LT tires.

Also, those who are doing the 10% reduction in P type tires should be aware that the 15% mentioned above is NOT included in that 10% - you need to do both.

[Vlamgat]

On the issue of load rating vs wheel size: I think the thread has moved a little off center over it 59 odd pages. The issue is not whether 15" wheels and tires can carry the load per the tire specs. Rather that the 15" tire production is almost universally made in China and because they are "trailer" tires, are not built to any standard. Yes there are numbers and letters on the sidewalls but there is significant doubt as to whether any of those numbers are true or accurate. Even rolling circumference differs between manufacturers. Whereas the 16" light truck tires at the D or E load ratings are subject to to the risk/reward of the wider consumer market of truck owners and tend (but not always as we were taught by Michelin) to be more robust, reliable and able to meet an operating environment at 80% of capacity on a predictable basis. This has been my experience (3 years) and seemingly that of other A/S owners.

[Ag&Au]

Originally Posted by CapriRacer

Ah ..... Mmmm ..... Not exactly.

I think tires should never be loaded to more than 85% of their rated capacity (which includes the adjustment if you are using a lower inflation pressure.)

This applies to ALL tires, not just LT tires.

Also, those who are doing the 10% reduction in P type tires should be aware that the 15% mentioned above is NOT included in that 10% - you need to do both.

OK, obviously you know what you are saying better than I do, but now I am confused.

Are you saying ALL tires, even when used in their intended service should never be loaded more than (their rated load-15%)? If that is the case why don't they publish the rated loads as 15% less, and eliminate the confusion? If that's not what you are saying, please clarify in what situations you recommend the 15% reduction. I though that was correction for P and LT tires on a trailer. Apparently that is what the 10% is. Correct?

I have spent my entire life with the belief that any system is designed with a safety margin above the max specs if used as intended. (I even applied this belief to my diapers when I was a baby) And if used as intended, the max specs are a safe and intended use. Is my bubble (or diaper) burst?



Ken

[dkottum]

Noting that it is tire engineers who developed the Good Year Marathon we love so dearly, I am am skeptical of their advice.

[SteveSueMac]

Originally Posted by CapriRacer

Ah ..... Mmmm ..... Not exactly.

I think tires should never be loaded to more than 85% of their rated capacity (which includes the adjustment if you are using a lower inflation pressure.)

This applies to ALL tires, not

Also, those who are doing the 10% reduction in P type tires should be aware that the 15% mentioned above is NOT included in that 10% - you need to do both.

Yes, I remember that, Capri. 85% of the derated capacity is 6745 for the set of 4 and I'm still almost 1000# under that limit according to scale tickets. I inflate to 50 PSI cold and my internal TPMS sensors tell me I never exceed about 30 degree F temp rise or 10% (really closer to 5-6%) pressure rise while traveling.

I almost switched out to a D-rated Goodyear Cargo LT (I want to say G26 or something like that?) but the profile would have dropped the trailer more than an inch and I didn't want to futz with the level hitch alignment I've got now. I may go that route in the future but for now am very happy with the Michelins.