Another Tire Inflation Posting

[SLO]

Sorry for the length of post. I have always had tire excessive wear and cupping on the inside and outside edges of all four ST235/85R16 G rates Sailun tires. I would generally attribute that to under inflation and some scuffing on tight, hard surface, turns. However, I’ve always kept inflation at 110 psi. Tire wear has been the same with original axles and with new IS suspension. When I recently had my tires installed on my new wheels the tire dealer suggested over inflation could cause this wear. WHAT!!!!

In my research I found this:

https://www.hendrickson-intl.com/getattachment/ac8c825c-b799-4a87-bac0-f75f746c747c/TMX_WhitePaper.pdf

Particularly this paragraph:


“Over-inflated tires are harder than properly inflated tires, making them more susceptible to tread surface cutting, punctures and impact breaks. Over-inflation also changes a tire’s footprint, which can affect tire traction and lead to irregular wear patterns. TMC Recommended Practice RP 219B, Radial Tire Wear Conditions and Causes, indicates that the probable cause of excessive wear found on both shoulder ribs of trailer tires in the study was likely over-inflation. The edges of an over-inflated tire pull away from
the ground and only make contact when they skip across road imperfections, or when the tire bounces with enough force to press the edges into brief contact with the road. That scuffing of the rubber causes rapid and irregular edge wear. This accelerated tread wear can cost 7 to 15 percent of the tire life.”

Sailun tire inflation chart:

https://fifthwheelst.com/documents/Copy%20of%20Load%20and%20Inflation%20All%20ST-Modified.pdf

At 110 psi the load capacity is 4400 lbs per tire. I haven’t had individual tires weighed but I doubt they are close to 4400 lbs. My weight on trailer axles is 12,680 lbs. My guess would be no more than 3860 lbs per wheel, which would be 90 psi. I know most who have posted your tire inflation figure, has stated 110 psi. Thoughts, feedback, disagreements on this uneven tire wear caused by over inflation would be appreciated.

 

[Dahillbilly]

Max psi isn't always the best. Correct inflation for the weight is the correct way to go. I know I've got to reweigh my TH when it's loaded so I'll have a better idea of what psi to use.

 

[RickL]

Best to weigh your unit as you would normally have packed when you travel. Unless you hit a rally where they can do individual wheel positions (the best you could do) weighing the axles independently at least provides you with what the axle is carrying. Both axles should be relatively close so if you find a significant difference between axles, say 5000 lbs on the front axle but 6000 lbs on the rear you need to move the weight around OR look at the ride of the trailer. If the nose is too high it transfers the weight to the rear axle.

Once you have the axles weighed inflate the tires to carry the heaviest weight. So if the rear axle is the heaviest, using the load and inflation chart adjust your tire pressure to carry that weight. So if your axle is 6000 lbs you would assume each tire is carrying 3000 lbs. so adjust you pressures to carry that. I don’t and have never subscribed to adding additional pressure to provide a fudge factor. The fallacy of this method is the assumption of each wheels weight. That is why individual wheel position weighing is your best option.

 

[centerline]

a trailer tire is designed with stiff sidewalls, and are not meant to have much flex in them.... if they are under inflated, they WILL heat up more than is safe.... so keeping them inflated to minimize flex will help the tire reach its full life potential...

if the tires are cupping, I would have an axle alignment done by someone who KNOWS what they are doing.... its not uncommon for trailer axles to be out of alignment, sometimes quite far.... it doesnt matter how new, how old, or what type or brand the suspension is, if the hangers are welded in the wrong place on the frame, the axles wont track true....

an unbalanced wheel/tire can also cause erratic tire wear, which having it balanced is the only cure..... sometimes shock absorbers can be added to help with tire wear, but the most likely cause is axle alignment issues...

 

[RickL]

a trailer tire is designed with stiff sidewalls, and are not meant to have much flex in them.... if they are under inflated, they WILL heat up more than is safe.... so keeping them inflated to minimize flex will help the tire reach its full life potential...

if the tires are cupping, I would have an axle alignment done by someone who KNOWS what they are doing.... its not uncommon for trailer axles to be out of alignment, sometimes quite far.... it doesnt matter how new, how old, or what type or brand the suspension is, if the hangers are welded in the wrong place on the frame, the axles wont track true....

an unbalanced wheel/tire can also cause erratic tire wear, which having it balanced is the only cure..... sometimes shock absorbers can be added to help with tire wear, but the most likely cause is axle alignment issues...

Trailer are NOT designed much different then passenger and or light truck tires. What really sets them apart is the tread depth and the compounds utilized in the tread, along with a more robust bead bundle. Some trailer tires may have a stiffer wedge installed near the bead area that would give the appearance of a stiffer sidewall.

Also, the reason tires heat up is something called sidewall jounce. These can be the result of lack of pressure, overweight conditions, and/or excessive speed. To visual this, take an old metal coat and cut out the length part. Then bend this rapidly. You feel the heat at the bend. That is what the tire feels as it is “jouncing” (Flexing).

Balancing the tire assembly will help tire wear, along with correct alignment. Having the correct tire pressure also will provide the best footprint pattern for the tire.

 

[centerline]

Trailer are NOT designed much different then passenger and or light truck tires. What really sets them apart is the tread depth and the compounds utilized in the tread, along with a more robust bead bundle. Some trailer tires may have a stiffer wedge installed near the bead area that would give the appearance of a stiffer sidewall.

Also, the reason tires heat up is something called sidewall jounce. These can be the result of lack of pressure, overweight conditions, and/or excessive speed. To visual this, take an old metal coat and cut out the length part. Then bend this rapidly. You feel the heat at the bend. That is what the tire feels as it is “jouncing” (Flexing).

Balancing the tire assembly will help tire wear, along with correct alignment. Having the correct tire pressure also will provide the best footprint pattern for the tire.

I think we had this discussion before... and I think we may be agreeing that the sidewall flex is the problem, and i will also agree that the tires are assembled similarly, but I wont agree that they are DESIGNED the same...
you can disagree with me and i can disagree with you, but for all practical purposes I can PROVE my opinions to be true.....

and it isnt rocket science.. all ANYONE has to do is take an ST tire, and an LT tire.... mount one on each side of a trailer, and load them to their maximum rated limit with full rated air pressure, and then run them down a hot summer time road at highway speed and see how they perform..... after about a hundred miles, stop and let 30% of the air out of each tire... then take off again.... only the un-informed will not be able to predict whats going to happen, and about how many miles it will take.... take an extra set of tires so on the return trip you can try it again to see if the first time was a fluke... if you are running the hot highways like in an arizona climate, it wont just be a "worst 2 out of 3", but you will have a 3 for 3 failure rate on the st tires... they wont take the flex, and the heat of the highway only adds to the heat that they create themselves when their sidewalls flex... and they will basically "explode" taking off fenders, steps, jacks or whatever else they can wrap themselves around as they come apart...

the worst one i ever had was on a travel trailer, where the tire came apart, with the tread face not coming fully loose from the tire, but hanging on the outer sidewall, and rotating with the wheel, which took off the plastic fender, some skirting braces, and all the while til i got stopped, the shredded steel beltings grinding a way the finish on the skin of the trailer til it ended up looking like some one took a 5 foot wire wheel on a grinder and held it to the side of the trailer..... an extremely expensive repair that neither the tire company or the salesman/tire store that sold them to me was willing to take any responsibility for....

for the most of my life, ive been pulling trailers across the country, and ive ran cheap tires and expensive tires... ive switched from st to lt, and tried different brands of both..... and ive talked to many many tire guys and the salesmen always have an excuse as to why or what may have happened, which, a "bad batch of tires" if the most common excuse..... but those of us who have the experience of traveling so many miles under harsh conditions, we know the difference between the 2 types of tires.... the ST tire needs to have its sidewall flex minimized to last, no matter if its a cheap brand or an expensive brand, and the LT is designed to have sidewall flex.... and if it doesnt flex its either dangerously over inflated or not carrying any load at all....

and they both ride/pull differently from one another. if the tires are carrying maximum load and you are driving hard on a winding road, the LT tires are going to feel a bit squishy on the corners, but the ST tires will stand up and trail along behind you like they are proud to be doing their job correctly......

BOTH the ST or the LT tires are fine, but which tire one chooses to run on their trailer, and the quality of them depends on how and where they drive, and how much load they carry, but the ST tire is much less forgiving to low air pressure.... and running maximum pressure with a light load on the ST tire wont result in such abnormal center wear like is usually seen on the maximum inflated LT tires....

so.... I will continue to offer my free wisdom to anyone who wants to extend their tire life, and you can offer your salesman advice to those who want or need a salesmans point of view, and with what we both have to offer, they can decide for themselves what works best for their use....

and for those that dont care, none of this matters anyway....

 

[RickL]

I think we had this discussion before... and I think we may be agreeing that the sidewall flex is the problem, and i will also agree that the tires are assembled similarly, but I wont agree that they are DESIGNED the same...
you can disagree with me and i can disagree with you, but for all practical purposes I can PROVE my opinions to be true.....

and it isnt rocket science.. all ANYONE has to do is take an ST tire, and an LT tire.... mount one on each side of a trailer, and load them to their maximum rated limit with full rated air pressure, and then run them down a hot summer time road at highway speed and see how they perform..... after about a hundred miles, stop and let 30% of the air out of each tire... then take off again.... only the un-informed will not be able to predict whats going to happen, and about how many miles it will take.... take an extra set of tires so on the return trip you can try it again to see if the first time was a fluke... if you are running the hot highways like in an arizona climate, it wont just be a "worst 2 out of 3", but you will have a 3 for 3 failure rate on the st tires... they wont take the flex, and the heat of the highway only adds to the heat that they create themselves when their sidewalls flex... and they will basically "explode" taking off fenders, steps, jacks or whatever else they can wrap themselves around as they come apart...

the worst one i ever had was on a travel trailer, where the tire came apart, with the tread face not coming fully loose from the tire, but hanging on the outer sidewall, and rotating with the wheel, which took off the plastic fender, some skirting braces, and all the while til i got stopped, the shredded steel beltings grinding a way the finish on the skin of the trailer til it ended up looking like some one took a 5 foot wire wheel on a grinder and held it to the side of the trailer..... an extremely expensive repair that neither the tire company or the salesman/tire store that sold them to me was willing to take any responsibility for....

for the most of my life, ive been pulling trailers across the country, and ive ran cheap tires and expensive tires... ive switched from st to lt, and tried different brands of both..... and ive talked to many many tire guys and the salesmen always have an excuse as to why or what may have happened, which, a "bad batch of tires" if the most common excuse..... but those of us who have the experience of traveling so many miles under harsh conditions, we know the difference between the 2 types of tires.... the ST tire needs to have its sidewall flex minimized to last, no matter if its a cheap brand or an expensive brand, and the LT is designed to have sidewall flex.... and if it doesnt flex its either dangerously over inflated or not carrying any load at all....

and they both ride/pull differently from one another. if the tires are carrying maximum load and you are driving hard on a winding road, the LT tires are going to feel a bit squishy on the corners, but the ST tires will stand up and trail along behind you like they are proud to be doing their job correctly......

BOTH the ST or the LT tires are fine, but which tire one chooses to run on their trailer, and the quality of them depends on how and where they drive, and how much load they carry, but the ST tire is much less forgiving to low air pressure.... and running maximum pressure with a light load on the ST tire wont result in such abnormal center wear like is usually seen on the maximum inflated LT tires....

so.... I will continue to offer my free wisdom to anyone who wants to extend their tire life, and you can offer your salesman advice to those who want or need a salesmans point of view, and with what we both have to offer, they can decide for themselves what works best for their use....

and for those that dont care, none of this matters anyway....

While yes I did sell tires, that was not my primary purpose in my 35+ yrs in the tire industry. Please tell me how many times you have been in a tire plant or for that matter how many different plants. I have had significant exposure to the construction of a tire, regardless of its purpose. My hands on expevidence in dealing with tire issues isn’t a result of what has just happened to me (for if it was it would be a very short history. One tire failure in 50+ yrs of driving). You may want to believe there are significant differences in ST and LT tires and what you want to believe is for your satisfaction. However all I am trying to provide is real insight and information. What the customer elects to do with that to make an informed decision is their responsibility.

 

[NYSUPstater]

Underinflated tires = KA-BOOM! That's the reason you see so many "gaters" as we semi drivers call them on the road from semis. Why do RV mfr's state tire PSI on data labels and for that matter, cars/trucks? If tire mfr's say that their brand of tires should be aired to "X" pounds for "X" weight on them, then they should provide that info. This kinda goes in line as to why we went w/ a DRW for our BC cuz we were over on the SRW tires capacity and at Hiway speed for long durations, high ambient air temps, high road temps, being over on tires........IMO spells a blowout in the making. Can/could happen w/ a DRW? Certainly but less likely. Tires aired up to mfr specs are designed just for that so they can withstand the extremes thrown at them.

 

[SLO]

I appreciate all the responses to my post. However, no one has addressed my original question of uneven tire wear on the inside and outside edges of all four wheels by this specific possible cause that was put forth in the link on post #1.

Quote: The edges of an over-inflated tire pull away from
the ground and only make contact when they skip across road imperfections, or when the tire bounces with enough force to press the edges into brief contact with the road. That scuffing of the rubber causes rapid and irregular edge wear. This accelerated tread wear can cost 7 to 15 percent of the tire life.

Proper tire inflation, ST, LT tires and sidewall stiffness have been discussed numerous times. My question is about this particular tire wear caused by over inflation. I have never heard of this tire wear cause before and it’s written by someone much smarter than I on this matter.


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[CapeCodGearJammer]

SLO,
We have a 2018 Bighorn 3270rs that came with the Sailun ST 235/85 R16 G rated tires.
We have the same exact wear on all 4 of our tires.
Both outside edges are worn and they have NEVER been underinflated!!!!

We monitor the pressures with a TPMS system.
I religiously check the pressures before each trip and closely monitor the pressures and temps of all 4 trailer tires as well as the truck tires while traveling!!!

I do not travel overloaded and I maintain the pressures @ 110 psi. as per the sidewall posting and data sticker on the rv.

Note: I recently had the trailer alignment checked and it needed a very minor adjustment.
I wanted to check it prior to replacing my tires.
I'm leaning towards replacing them with the Sailun's that came with the trailer.

Now I'm curious to see if I'm running them over pressure.

We were on the road full-time for 3 years until last October.

 

[CoveredWagon]

I have the exact same year make and model and the same tires, with the same tire wear patterns.
When I had the combination weighed, each wheel with and without the trailer, I was given a tire inflation chart. It was marked that I should inflate to 75psi. THAT'S NUTS. if that were correct then at 110psi I should be way over inflated which with conventional thinking should be wearing out the center of the trailer tires. Not so. My tires look exactly like the pictures. Inside and outside rib, all four tires.

 

[SLO]

CapeCodGearJammer,

Thanks for the pics. That’s the exact wear pattern I have that I referenced in my original post.


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[RickL]

I see potentially a few things, it appears from the pictures there is some cupping on the tread. Also, I have seen some of that edge wear result from incorrect torquing of the wheel bearings. I’m not saying it is a wheel bearing issue, but it’s something to eliminate. When they checked the alignment did they just adjust toe in? Did they provide you a printout with toe and camber?

Additionally, adjusting the tire pressure to the actual known weight will go a long way in promoting the best tire wear.
The attached pictures are of my tires with approximately 30,000 miles. They are also the OE Saliun’s.