Tire pressure vs wear

[U.S.ArmyVeteran]

Originally Posted by Mike134

your reading comprehension seems to be lacking........
.

Ad hominem attack's are always helpful in proving your point.

[krazyk]

I dont see how these tire threads get so absurd. Go by what is stamped on the tire sidewall. Simple and easy to understand. Inflating to MAX COLD PSI saves tires, fuel, and lives.



Unless you are pulling yout RV trailer non stop everyday, I doubt you will wear out a set of quality tires by running max PSI. RV trailer tires are much more likely to "age out" not "wear out".



Castle Rocks excepted. They are much more likely to "blow out" than do anything else.

[Mike134]

Originally Posted by krazyk

I dont see how these tire threads get so absurd. Go by what is stamped on the tire sidewall. Simple and easy to understand. Inflating to MAX COLD PSI saves tires, fuel, and lives.

I've found this to be more helpful for setting the proper pressure on my GY Endurance tires. I'd only run max pressure if the tire was loaded to the max.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

[Airdale]

For many years people like me that have been writing about RV trailer tires have constantly lobbied for trailer tires to provide load capacity reserves, something like the automotive side of the house. In the past, NHTSA rules committees, for one reason or another rejected the load capacity reserve request and consumers still had unacceptable amounts of catastrophic tire failures. Trailer manufacturers were adding weight faster than the tires industry could keep-up with. In today’s market, thanks to the RVIA organization, we have Original Equipment RV trailer tires with a minimum of 10% in load capacity reserves on new trailers.

So where am I leading you to with this? Do Not Inflate Trailer Tires To The Load Carried. It hasn’t worked in the past and it won’t work now. Probably the most standing-out reason is one tire on an axle carries more weight than the other. Load capacity reserves have helped tremendously in saving tires from being overloaded.

The ST tire market has and is keeping-up with the times. Some of the designated sizes have as many as 5 load ranges to choose from. Steel cased tires are available for all of those axles 7000# and higher. Why do consumers feel it’s necessary to fool around with inflation pressures for RV trailer tires? The trailer manufacturer has insured the OE tires meet minimum standards. Minimums don’t vary. They must be consistent for the field to be protected. NHTSA says the correct inflation pressures for your tires are displayed in the vehicle owner’s manual, tire load and inflation placard and on the vehicle federal certification label. What justifies using less? Tire industry standards require replacement tires to have a load capacity equal to or greater than what the OR tires provided (via inflation). The actual inflation pressures may not be the same as OE tire pressures but the end result is the same.

Every road tire has, molded into its sidewall the maximum load capacity it can provide. It also has the cold inflation pressure needed for it to provide that load capacity. That inflation pressure is in no way a recommendation.

BYE, BYE!

[Mike134]

Originally Posted by Airdale

So where am I leading you to with this? Do Not Inflate Trailer Tires To The Load Carried.

I have to disagree.

My trailer label specs 205-14 (c load range) tires to be inflated to 50 PSI to carry 1750 lbs.

I've upgraded to GY 215-14 (D load range) with a sidewall max pressure of 65 psi

No way will I run them that inflated because my contact patch with the road will be greatly diminished increasing my braking distance.

50 PSI works well and gives a full contact patch.

SEE YA!!

[TitanMike]

Originally Posted by Airdale

For many years people like me that have been writing about RV trailer tires have constantly lobbied for trailer tires to provide load capacity reserves, something like the automotive side of the house. In the past, NHTSA rules committees, for one reason or another rejected the load capacity reserve request and consumers still had unacceptable amounts of catastrophic tire failures. Trailer manufacturers were adding weight faster than the tires industry could keep-up with. In today’s market, thanks to the RVIA organization, we have Original Equipment RV trailer tires with a minimum of 10% in load capacity reserves on new trailers.



So where am I leading you to with this? Do Not Inflate Trailer Tires To The Load Carried. It hasn’t worked in the past and it won’t work now. Probably the most standing-out reason is one tire on an axle carries more weight than the other. Load capacity reserves have helped tremendously in saving tires from being overloaded.



The ST tire market has and is keeping-up with the times. Some of the designated sizes have as many as 5 load ranges to choose from. Steel cased tires are available for all of those axles 7000# and higher. Why do consumers feel it’s necessary to fool around with inflation pressures for RV trailer tires? The trailer manufacturer has insured the OE tires meet minimum standards. Minimums don’t vary. They must be consistent for the field to be protected. NHTSA says the correct inflation pressures for your tires are displayed in the vehicle owner’s manual, tire load and inflation placard and on the vehicle federal certification label. What justifies using less? Tire industry standards require replacement tires to have a load capacity equal to or greater than what the OR tires provided (via inflation). The actual inflation pressures may not be the same as OE tire pressures but the end result is the same.



Every road tire has, molded into its sidewall the maximum load capacity it can provide. It also has the cold inflation pressure needed for it to provide that load capacity. That inflation pressure is in no way a recommendation.



BYE, BYE!

What you say is correct as long as the owner doesn't decide to upgrade tires by one or more load ranges. If OE tire had plenty of reserve capacity at max cold inflation pressure, let's say a C load range @50 psi, and new tire is an E load range, 80 psi is going to be ridiculously high for the load carried.

The MAIN issue to keep tires inflated properly to begin with.

[Airdale]

Originally Posted by TitanMike

What you say is correct as long as the owner doesn't decide to upgrade tires by one or more load ranges. If OE tire had plenty of reserve capacity at max cold inflation pressure, let's say a C load range @50 psi, and new tire is an E load range, 80 psi is going to be ridiculously high for the load carried.

The MAIN issue to keep tires inflated properly to begin with.

Darn it, you've suckered me right back in here.

Adding a load range to a designated size does not change the minimum inflation pressure. Optional inflation pressures have always been available between vehicle manufacturer recommended cold and sidewall max.

[phillyg]

Quoting Airedale, in part, who got sucked in again , "......Do Not Inflate Trailer Tires To The Load Carried. It hasn’t worked in the past and it won’t work now. Probably the most standing-out reason is one tire on an axle carries more weight than the other.......Why do consumers feel it’s necessary to fool around with inflation pressures for RV trailer tires? The trailer manufacturer has insured the OE tires meet minimum standards. Minimums don’t vary. They must be consistent for the field to be protected. NHTSA says the correct inflation pressures for your tires are displayed in the vehicle owner’s manual, tire load and inflation placard and on the vehicle federal certification label. What justifies using less?....."

I see no reason not to use tire mfgrs'. load tables to adjust psi downwards if the load allows. Why would any tire mfgr. even publish a table if everyone should just use the max psi embossed on a tire. I agree in most cases each axle carries a different load and is unequal side-to-side, but I don't trust RV mfgrs. to always do the right thing. We can't even trust them to build units to their own specs. And, correct me if I'm wrong, that portion of the NHTSA you cite only applies to passenger and light trucks.

Regardless, most folks that weigh their rigs use CAT-type scales rather than getting individual wheel weights (which is better). But even knowing individual wheel weights, psi should still be set to that needed on the heaviest wheel, yes? If you only know the weight on all axles, dividing by the number of wheels, gets you close to the needed psi (based on the load tables). The alternative is to always use max psi in all tires, which can result in an over-inflated scenario where center tread wear is increased and/or a rougher ride. I'll stick with the load tables if I know my weight.

[krazyk]

Why do consumers feel it’s necessary to fool around with inflation pressures for RV trailer tires?

What Airdale is trying to tell you is that if your RV came with crap LR "C" tires and you replace them with high quality LR "D" tires, DO NOT DEFLATE them to a lower PSI just because they have a higher capacity than the original marginal crap tires.



RV's are usually near their max GVWR all the time. Passenger cars are not. Always go by the MAX COLD PSI on the trailer tire itself not the RV label. It no longer applies because you upgraded the tires. How does anyone not understand this?


To believe you will wear out your RV tires by running MAX COLD PSI stated on the tire is not realistic.

[Airdale]

Excerpt from a USTMA RV tire manual.

"Inflation pressure recommendations may also be determined based on the tire manufacturer’s specifications, which define the amount of inflation pressure necessary to carry a given load. These inflation pressures may differ from those found on the vehicle tire placard or certification label.

However, never use inflation pressure lower than specified by the vehicle tire placard, certification label or owner’s manual. Nor should inflation pressure exceed the maximum pressure molded on the tire sidewall."


All highway RV trailer tires and others have the DOT symbol on their sidewalls. Because they have different designations does not distract from the fact that they are all governed by the same FMVSS standards. All automotive tires have mandated inflation pressure reserves set by the vehicle manufacturer. In the same standard RV trailer tires are nor required to have more load capacity than the GAWRs require. Consumers not familiar with standards and regulations most often believe automotive tires are stronger because they have reserves. Not so, they provide what the load inflation charts display at the increments approved and standardized by the TRA. The official standard for autos is the load index numbering system. For LT & ST tires it's the load range lettering system. You will find the load index system on LT & ST tires for the purpose of displaying the tires speed letter as a suffix.

The trailer manufacturer is not required to set any load capacity reserves with the OE tires. The standard does tell them that their selection must be appropriate for that fitment. That means the tires must - via inflation pressures - provide a load capacity equal to or greater than the vehicle certified GAWRs. (Kicker: RVIA, a powerful RV trailer membership association has recommended/mandated a 10% load capacity reserve for all OE tires.)

Tire inflation charts are not a carte blanche tool to be used by consumers. Their primary purpose is for setting recommended cold inflation pressures by vehicle builders and tire installers. They are not recommendations, they set recommendations. Once made widely public by the WWW all sorts of user opinions followed. Actually, the purpose for consumer access to load inflation charts is their need when using plus sized tires.

[jadatis]

Reaction to post# 68 2 post already above here

In basics , following the pressure/ loadcapacity- lists of your tire, should be right.....BUT.

Using on weighed axleloads, you have to be ware of R/L unbalance, can sometimes be 45/55% .
Then you think , OK use the 55% so 10% adding to the weighed load.
And if axle end loads weighed use the highest on the axle ( because for some reason pressure needs to be the same on the axle).

But then you can still go wrong.
1. St tires in the bigger sises are maximum load determined for 65mph, while LT for 99mph. Gives 6 loadindex steps higher maxload is about 18%.

Then if you drive 70mph, the tires slowly overheat, so rubber goes above its critical temperature, at wich it hardens, and internal beginning crackes are made, wich dont disapear, and grow in time .
This may only happen ZERO times in a tires used time.

And how accurate was the weighing, and was everything in it, and on the same place, as you go on tripp.

2nd the lists in US used for ST tires are made with a formula that leads to higher loadcapacity for the pressure then US LT lists, and even higher the EUR lists for every kind of tyre used.
So in the lower pressures the loadcapacity is to high, so you loose a part of the reserve.

Then 3th
Going to a higher loadrange, the US lists calculate loadcapacity for one loadrange and place the other loadranges maxload at their belonging " max " pressures in that list.
Now a higher loadrange calculates a lower loadcapacity for the same pressure, so you will read a lower pressure at the loadcapacity you determined to be needed. Also this can give tirefailure by overheating once to often ( so more then ZERO times in tires live).

That is why I calculate in my made spreadsheets a highest pressure that wont give bumping. So maximum reserve. And I use an even saver formula then the european, and use 90% of the loadcapacity belonging to the pressure.
This all to cover inacuraciesin pressure and weight determination, pressure loss in time, shifted load R/L, and what I might forget now. I also substract first 6 LI steps of ST .

For who is interested, the basic formula for calculating loadcapacity for a pressure is next

Loadcapacity = maxload x ( P/Pr) ^X.
In wich :
P is the pressure you want loadcapacity for
Pr is referencepressure, what most think is max.
^X is a power like ^2 is square and ^0.5 is root.
For ST ^0.585 is used , same as old diagonal tires.
For LT ^ 0.7 is used
In europe ^ 0.8 is used for decades for every kind of tyre. Since 2006 also in US for P-tires. Before 2006 for P-tires ^0.5 ( root) was used, wich gave even higher loadcapacity's then the diagonal and ST ( ^ 0.585).
The higher this power ^X , the lower loadcapacity for the pressure, and power ^1 is lineair calculation, so fi 80% of Pr gives 80% of maxload.
In fact lineair calculation some do, is not that bad.

[plocklin]

Originally Posted by Airdale

The minimum operating pressure for your tires is displayed on tire labels/placards on the side of your trailer.

Normally there is no gap between what the vehicle manufacturer has recommended and the maximum PSI on the tire sidewall.

The tire sidewall pressure is not a recommendation, it provides the tire with an inflation pressure that will produce the maximum load capacity from the tire.

If your tires are inflated below what the trailer placard says, they are under-inflated.

If they are inflated above the "max psi" listed on the tire, they are over-inflated.

Anything within this range can be an adjustment for ride and tread wear.


- What Airdale said

[TitanMike]

Originally Posted by plocklin

If your tires are inflated below what the trailer placard says, they are under-inflated.

If they are inflated above the "max psi" listed on the tire, they are over-inflated.

Anything within this range can be an adjustment for ride and tread wear.


- What Airdale said

Tires checked on a cold morning can be underinflated if they were checked and adjusted on a "warm" morning the day before.

"Cold inflaion pressure" merely means the pressure in a tire when it hasn't been driven long enough for tire temp to equalize with ambient temp. Frequent checks when changing climates is essential however NEVER LET AIR OUT OF A WARM/HOT TIRE.

It's the air pressure that's carrying the load and it's easy to start out on an under inflard tire on a frosty morning when your last pressure check was on a 60-70 degree morning.

[Airdale]

Originally Posted by plocklin

If your tires are inflated below what the trailer placard says, they are under-inflated.

If they are inflated above the "max psi" listed on the tire, they are over-inflated.

Anything within this range can be an adjustment for ride and tread wear.


- What Airdale said

Yup! There is a lot of history linked to the reason RV trailer manufacturers choose and fitted RV trailer tires back in the day. Some long time ST tire builders such as Carlisle set a lot of early precedence in the way they wanted their tires to be used. They published almost all of them and for a number of years they were mimicked throughout the industry.

RV trailer manufacturers have always, and still do, provide OE tires that meet minimum standards. By doing so they lock themselves into having to set recommended cold inflation pressures to equal what the tire needs to provide its maximum load capacity. So, when plus sized tires are used or same designated sizes with a higher load capacity are used the consumer/installer will automatically assume they must set the inflation pressures to sidewall max. Why would you do that? All you need from plus sized tires is a load capacity that provides a load capacity reserve you are satisfied with.

[krazyk]

For who is interested, the basic formula for calculating loadcapacity for a pressure is next

Loadcapacity = maxload x ( P/Pr) ^X.
In wich :
P is the pressure you want loadcapacity for
Pr is referencepressure, what most think is max.
^X is a power like ^2 is square and ^0.5 is root.
For ST ^0.585 is used , same as old diagonal tires.
For LT ^ 0.7 is used
In europe ^ 0.8 is used for decades for every kind of tyre. Since 2006 also in US for P-tires. Before 2006 for P-tires ^0.5 ( root) was used, wich gave even higher loadcapacity's then the diagonal and ST ( ^ 0.585).
The higher this power ^X , the lower loadcapacity for the pressure, and power ^1 is lineair calculation, so fi 80% of Pr gives 80% of maxload.
In fact lineair calculation some do, is not that bad.

I sincerely hope this post was a joke but Im going to comment anyway.


I propose that Congress pass a law which requires every towed RV trailer be equipped with an on board computer capable of at least 2GHz processor speed to monitor ambient temp, tire temp, speed, humidity. etc. and make constant pressure adjustments using an onboard nitrogen producing system and compressor. The added cost must be limited to no more than $20,000 per unit. This should eliminate owners obsession with load capacity and tire pressure.

[jadatis]

No yoke, yust facts collected in 14 years

[TitanMike]

Originally Posted by krazyk

I sincerely hope this post was a joke but Im going to comment anyway.


I propose that Congress pass a law which requires every towed RV trailer be equipped with an on board computer capable of at least 2GHz processor speed to monitor ambient temp, tire temp, speed, humidity. etc. and make constant pressure adjustments using an onboard nitrogen producing system and compressor. The added cost must be limited to no more than $20,000 per unit. This should eliminate owners obsession with load capacity and tire pressure.

It's not just tire pressure and load many are obsessed over. The obsessions range from tires to batteries, roof sealants, toilet paper, and tank chemicals to name a few.