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Old 08-09-2021, 06:59 AM   #1
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Tire pressure vs wear

I have a single axel 4,4400 lb F/R FSX toy hauler. It has Castle Rock 270/45/15 tires. It has green valve stem caps which i think, means the tire is inflated with nitrogen to make the tire stay cooler and keep a constant tire pressure when traveling. With 5K - 6K miles.

The tire wear indicator says if the tire is wearing in the middle of the tread, (which both of mine are) it means the tire is OVER inflated.

The sticker on the side of the trailer says to inflate tires to 65 lbs. I reduced the tire pressure to 55 lbs. to level out the tread wear.

My question is: is this a good idea? Or: should I just inflate to 65 lb and let the tires wear as it will?
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Old 08-09-2021, 07:22 AM   #2
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What does it say on the sidewalk of the tire with regard to cold inflation? I agree if the center is wearing out they are over inflated. If you are a NASCAR racer nitrogen in the tires if very important not so much so for the regular camper. Adjusting the air pressure to match the rigs load can very much improve the tire wear. 10 psi is a big drop. If you are going to be adjusting invest in a TPMS. JMHO
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Old 08-09-2021, 07:37 AM   #3
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In theory, the tires should be inflated to the sidewall max. Which is what I have always done with the exception of the cargo trailer tires which are up-rated in load capacity. I then ran those a little lower. In several decades and quite a few trailers from boats to TH's, I have never had a tire wear dramatically different in the center. Granted, the trailers were almost always loaded. So maybe you are packing really light?
Adjusting a couple psi is not a big deal. Just use dried air or nitrogen. Just don't use the coin operated machine. Go to a real service station (their compressors have filters and driers on them) and use theirs. Some tire shops even have nitrogen top off for free. Nitrogen is not important, although it is 99.9% moisture free. The key is keeping water and oil out of your tires.
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Old 08-09-2021, 08:29 AM   #4
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Inflating the tire to its max with a light load can lead to a wear pattern of over inflation. Have your trailer loaded like you would normally have it for a trip, get it weighed, then inflate the tires to the inflation noted for its load. If you feel more comfortable then add some PSI to what the charts indicate. If you can’t find a chart from Castle Rock then use an ST tire inflation chart.
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Old 08-09-2021, 08:46 AM   #5
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There are hundreds of reports of Castle Rock tires exploding because of belt separation you may want to get another tire on there... Goodyear Endurance and Carlisle's are popular choices. Otherwise I would reduce the tire pressure from 65 to 61-62. If you go too low you run the risk of overheating the tire. So keep an eye on the temp of the tire by using a TPMS or just use the back of your hand so monitor the sidewall temps at every stop you make.
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Old 08-09-2021, 09:09 AM   #6
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The advice you got is solid. The nitrogen thing ... Don't get me started. A tire full of air was mounted on a rim, likely in a humid not air conditioned space. That was 78% nitrogen, some oxygen, and moisture. Then about 100% dry nitrogen was used on top of it to fill it the rest of the way. A commercial air compressor with a dryer does the same thing. The difference is a handful of percent of N and nothing else.

Your observations that the tire pressures need to be correct for the use is correct. Delaying tire pressure maintenance to find a nitrogen station might be pendantic.

Monitoring tire wear is a tough way to find the right pressures. It takes to long. You can draw a chalk line across the tread (kids sidewalk chalk) and tow it loaded across a big flat parking lot. The highest pressure (below sidewall max) that yeilds 85% or more chalk removed from the tread width is likely good. If the chalk is always removed, run max sidewall psi.
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Old 08-09-2021, 09:24 AM   #7
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If the tire label says 65psi put 65psi in them. And replace as they wear out.

Overloaded and underinflated tires blow out -- explode -- rather than just going flat. This is due to excessive flex and heat buildup caused by the soft sidewall which weakens the tire and the reason inflation to maximum cold sidewall pressure is required. Sure these are radials but you need need rigid sidewalls in trailer tires. Semi trailers commonly use radials and their sidewalls are brick rigid -- no flex.

Radial tires on passenger cars are designed for a soft sidewall and soft ride. ST tires are not.

Nitrogen in tires is a scam designed to sell overpriced air.

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Old 08-09-2021, 10:52 AM   #8
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When you ask about tire inflation, you will get plenty of answers on both sides. I know I've gone down that rabbit hole before. You will get as many telling you to always inflate to maximum cold pressure as those who say it is not needed and then give many different methods on how to determine where to set it. Who is right? I don't know. But I had never run max cold air pressure on anything including my cars trucks, and other vehicles until I got this camper. I did start doing that initially and several times ended up on a couple roads where I felt like I was in a shaker cup that was making a martini. Up and down quick shaking. I didn't like it. So I looked for a reasonable solution to this.

Standard disclaimer, I am in no way an expert but rather an enthusiast. I am not telling you this is the only way to do it. I am just letting you know what I am doing.

And I found this article.
https://fromnesttolife.com/tips/calc...trailer-tires/

So on my last trip from Wisconsin to the Smoky Mountains, I tried it out. My trailer loaded weighs in around 6300lbs. The tires on my camper are ST205/75R14/D Ridgway Sports tires. They have a max psi/load rating of 65psi at 2080lbs. So it is a dual axle and total load rating of all 4 of the tires would be 8120lbs. So dividing the weight of my loaded trailer by the load rating shows I'm at just under 78% of the rating
63008120= 0.775862
So using this, I took the max psi (65psi) and multiplied it by 0.78 as the max load is 8120 and I am only at 78% of max load and come up with this: 65 x 0.78= 50.7
So this would say that 51psi would be the ideal pressure but it seemed like to big a drop so I went up to 55psi. The article said to add 5% to the final calculation as a buffer which would have been 53.55psi. I probably went around 1700 miles on this trip and it felt much better. I did get 2 or 3 more minor martini shaking incidents but not as extreme as before. Although I didn't have one of those temperature guns to check, I checked the tires with my hands and couldn't feel any excessive heat as a result. Handling seemed just fine. So I will try it at 55psi for a couple more trips and see.
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Old 08-09-2021, 01:40 PM   #9
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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.
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Old 08-09-2021, 01:48 PM   #10
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[QUOTE=adaycjYou can draw a chalk line across the tread (kids sidewalk chalk) and tow it loaded across a big flat parking lot. The highest pressure (below sidewall max) that yeilds 85% or more chalk removed from the tread width is likely good. If the chalk is always removed, run max sidewall psi.[/QUOTE]

If you havent weighed your trailer ready to tow and adjusted the pressure to the tire makers inflation chart, the above mentioned information is the way to tell that the tire is at the proper inflation for the weight is is hauling.

I do this to my personal truck and like to see the chalk removed all the way to 1/8-1/4 of the inside/outside edge.
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Old 08-09-2021, 01:54 PM   #11
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Quote:
Originally Posted by Airdale View Post
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.
One must keep in mind that the manufacturer puts on tires that are "JUST" capable of carrying the trailer GVWR minus tongue weight. If one upgrades the tires to a higher rated tire, then the "maximum" on the tire is not the correct pressure, according to the tire manufacturers. I tend to trust the tire side of the equation over the trailer assembly company. I hold to the doctrine that states, weight your actual trailer as loaded, and use the tire specs for your tire and that load + 5-10% safety factor.
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Old 08-09-2021, 02:29 PM   #12
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Quote:
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There are hundreds of reports of Castle Rock tires exploding because of belt separation you may want to get another tire on there... Goodyear Endurance and Carlisle's are popular choices. Otherwise I would reduce the tire pressure from 65 to 61-62. If you go too low you run the risk of overheating the tire. So keep an eye on the temp of the tire by using a TPMS or just use the back of your hand so monitor the sidewall temps at every stop you make.
I fully agree with the above quote.. get rid of those Chinese Castle Rock tires and gain the assurance you won't have tire problems on the Road..! Get some Goodyear Endurance.. SEE:
https://www.discounttire.com/tires/t...goodyear-tires
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Old 08-09-2021, 04:30 PM   #13
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One must keep in mind that the manufacturer puts on tires that are "JUST" capable of carrying the trailer GVWR minus tongue weight. If one upgrades the tires to a higher rated tire, then the "maximum" on the tire is not the correct pressure, according to the tire manufacturers. I tend to trust the tire side of the equation over the trailer assembly company. I hold to the doctrine that states, weight your actual trailer as loaded, and use the tire specs for your tire and that load + 5-10% safety factor.
I'm a long time poster of tires used on RV trailers. I only post what is an accceptable standard for tire maintenance and replacements. Some don't like my "Joe Friday" approach.

There is a RVIA recommendation in place for trailer manufacturers to provide 10% in load capacity reserves. Just about everything from 2017 on will have that 10%.

Tire maintenance is based on the size and load capacity of the OE tires. Replacement tires get their minimum load and cold inflation values from what the OE tires provided. The correct tire pressure for your tires was set by the vehicle manufacturer and displayed on labels/placards affixed to the trailer. The maximum tire pressure is found on the tire sidewall (it is NOT a recommendation). Anything in-between is optional.

When adding a load range with replacement tires the consumer gains load capacity reserves via an increase in cold inflation pressures. If the tire designated size on the trailer's certification label is not changed with a larger replacement tire the load inflation chart works for all load ranges within the designated size of the OE tires. (Load Range is not part of a tire's size).

When using "plus sized tires" as replacements, they must have the capability to provide the load capacity the OE tires provided at the trailer manufacturers recommended cold inflation pressures. The installers of plus sized tires have the responsibility for setting a new cold inflation pressure that will provide, at the minimum, a load capacity the OE tires provided. Other considerations for plus sizing is wheel/rim size and valve stem PSI limit. Of course they must not cause any obstructions in the wheel wells.

Note: A designated size is like this; ST225/5R15 it has 4-5 load ranges. The same load inflation chart is used for all load ranges.

Another note: Original Equipment RV trailer tires are selected according to the vehicle's certified GAWRs.
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Old 08-09-2021, 06:15 PM   #14
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Agree with Rolland, post#4: If you're loaded to the max weight for your trailer, then inflate to maximum pressure. The tread on the tires will then contact the road evenly across the tire. If you're not at max weight, then run about 2-3 pounds under: again, the tread will have maximum grip on the road and they will not overheat.

The tires on my 5'er are Goodyear Endurance and the max air pressure is 80#. I normally run them at 78#. Tire wear has been even for the last 10K miles.
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Old 08-10-2021, 12:22 PM   #15
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What Goodyear Says

Quote:
Originally Posted by Jay45 View Post
I have a single axel 4,4400 lb F/R FSX toy hauler. It has Castle Rock 270/45/15 tires. It has green valve stem caps which i think, means the tire is inflated with nitrogen to make the tire stay cooler and keep a constant tire pressure when traveling. With 5K - 6K miles.

The tire wear indicator says if the tire is wearing in the middle of the tread, (which both of mine are) it means the tire is OVER inflated.

The sticker on the side of the trailer says to inflate tires to 65 lbs. I reduced the tire pressure to 55 lbs. to level out the tread wear.

My question is: is this a good idea? Or: should I just inflate to 65 lb and let the tires wear as it will?
FOR TRAILERS, GOODYEAR SAYS: "Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up." (emphasis supplied)

https://www.goodyearrvtires.com/weighing-your-rv.aspx

This may be less important for lighter trailers and for single axle trailers, where bouncing around could happen if your tires are way underloaded.

For heavy tandem axle trailers, interply shear is the number 1 tire enemy, and the best defense for that is higher pressure in quality tires built especially for loads induced by heavy trailers.

If my trailer is not light enough to bounce around and as long as the contact patch is full, I'm using at least 90% of the max sidewall pressure. I know and understand why some say there is an issue with impact damage if you have more than "optimum" pressure based on some weight/percentage formula. That's fine and everyone who likes those formulas can use them, but I'll take the safety factor to reduce interply shear to the minimum and the unquestionably reduced running temperature over all other considerations.

Until someone presents a very convincing argument to do something different, I will do what Goodyear recommends: Run Max Sidewall Pressure for loaded trailers.

For more on interply shear and pretty much everything you ever need to know about RV tires, here is a good place (and maybe the best place) to start:

https://www.rvtiresafety.net/search/...terply%20Shear
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Old 08-10-2021, 01:52 PM   #16
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FOR TRAILERS, GOODYEAR SAYS: Until someone presents a very convincing argument to do something different, I will do what Goodyear recommends: Run Max Sidewall Pressure for loaded trailers.
IMO, GY is describing what to do with OE tires. "Plus Sizeing" tires or going up to higher load ranges is another matter.
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Old 08-10-2021, 02:16 PM   #17
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Quote:
Originally Posted by Jay45 View Post
I have a single axel 4,4400 lb F/R FSX toy hauler. It has Castle Rock 270/45/15 tires. It has green valve stem caps which i think, means the tire is inflated with nitrogen to make the tire stay cooler and keep a constant tire pressure when traveling. With 5K - 6K miles.

The tire wear indicator says if the tire is wearing in the middle of the tread, (which both of mine are) it means the tire is OVER inflated.

The sticker on the side of the trailer says to inflate tires to 65 lbs. I reduced the tire pressure to 55 lbs. to level out the tread wear.

My question is: is this a good idea? Or: should I just inflate to 65 lb and let the tires wear as it will?
I have the same tires with the green valve stem cap......that does not necessarily mean they are nitrogen filled. Mine are not. I run mine at the cold tire pressure always. They are "china bombs" so I make sure to check the tire pressure every time I stop. My goal is to upgrade, but figure I will try to get as much use on them as I can. Right now, I only have maybe 3500 miles on them in the year I have owned. Figure keeping the pressure checked regularly should help.
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Old 08-10-2021, 03:01 PM   #18
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Ever wonder why the ST tires on your new trailer have maximum load capacities very close to the GVWR of the trailer? Folks complain about "marginal" tires all the time. If you fit tires with higher capacities in the common belief that they're somehow better you can get a couple of unanticipated and linked liabilities.

1. If run at maximum sidewall pressure you'll get wear in the center of the tire (but no other liability). So what? All ST tires are expected to do is support the trailer and tag along. They're not driven nor do they steer.

2. If you under-inflate the tire (say to equalize tread wear) you'll get a soft sidewall which will constantly flex and build up heat in the tire. Too much flex and heat will increase internal pressure and in extreme cases can cause a tire to explode. And the soft sidewall can cause instability in the trailer. A couple of psi won't make any difference of course.

These effects are minimized with the right size tires.

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Old 08-10-2021, 04:13 PM   #19
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Yes running on over inflated tires will cause the center to wear faster. My question: how many miles are you pulling the trailer? I expect it will take thousands of miles to show any increased wear, especially on a single axle trailer.

On a multi-axle trailer, I follow the recommendation of Roger Marble to run at max inflation pressure to minimize inter-ply shear damage which can occur at every turn the trailer makes.
For you, the correct inflation pressure is determined by the weight on the tires. Go get the trailer weighed, preferable getting individual tire loading. With individual tire weights, use the higher weight and inflate accordingly. If you can only get axle weights, divide by 2 and then add 10%. Trailers rarely have equal weights side to side. Mine is 100 lbs heavier on the driver side. So adding 10% covers the probability of unequal loads. Use this number to determine correct inflation.
Note that you can use the inflation chart from any tire manufacturer. There are only 3 charts, one each from agencies in either the US, Europe, or Japan. All are very close to each other. My understanding is that the US chart is the most generic, followed by Europe which is more used for their performance tires, then Japanese.

Bottom line, don't guess about correct inflation - get the weights. Also the correct pressure is set each day before hitting the road when the tires are still cold. Do not reduce the pressure as the day warms and the tires heat up.
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Old 08-10-2021, 05:29 PM   #20
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I would take a guess and say the tires are about to fail.
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