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PostPosted: Sun Oct 13, 2013 5:52 pm 
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I built out a Harbor Freight 1195-lb folding trailer like so many on this forum have recommended. One season later, less than 500 miles use with only my PA14 on the trailer, the tires were bald. The recommended tire pressure in the instruction manual was 60 PSI. After noticing the wear pattern, I backed this down to 45 PSI and eventually 35 PSI, but still got only 1 season of use on the factory tires. I just replaced with Carlisle Pro Scout tires and want to avoid the same problem.
What tire pressure do you use for your PA trailer?


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PostPosted: Sun Oct 13, 2013 6:52 pm 
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What is the load range and the size of the tires? With that in hand you should be able to find a load chart which could help you decide what minimum you need. To be on the safe side you can simply go to the max pressure listed on the side wall. By the way, I did a quick search to look at Carlisle Pro Scout and could not find them on the Carlisle website or else where.

If you wear out a set of tire in less than five hundred miles, you may have a serious alignment problem and not a tire pressure issue. Does the trailer crab when you pull it? Measure the center-line of the hub to the center/axis of the hitch/ball on each wheel to be sure they are essentially the same. Then try to measure toe in/out on the wheels relative to one another. They should be parallel. You can use a straight edge parallel to the ground pressed against the tires at the center-line and measure the distance between them on the front and the rear. This is a rough measurement but if you can find any significant difference this may be your problem (i.e. toe in or toe out) since they should be parallel.

By the way, I am betting the tires on the trailer from HF aren't great to begin with and I wonder if they are highway rated.

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Alan
2012 PA14 Papaya
2014 PA14 Dune

"If you must choose between two evils, pick the one you've never tried before!"


Last edited by Alphonse on Sun Oct 13, 2013 7:45 pm, edited 1 time in total.

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PostPosted: Sun Oct 13, 2013 7:31 pm 
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My Hobie Trailex trailer is lighter weight than the HF trailer and my 4.8 x 8 tires are max load rated @ 509# and inflated to 60 psi.
However, Trailex specifies the tires be inflated to on 12-15 psi......I have my PA-14 on this trailer and easily have over 500 miles on the tires...they look just like new when inflated to 14 psi.

Assuming your alignment is good, I would guess 20-22 psi is sufficient for your tires with only a PA-14 as the load.

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PostPosted: Sun Oct 13, 2013 9:24 pm 
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Alphonse - thanks for the advice on determining alignment. The trailer seems to track straight behind the truck with no fishtailing, so I was not too suspicious of misalignment. The wear pattern was pretty much bald down the center of the tire with preservation of tread toward both edges which is why I thought it was overinflation at anywhere from 60 down to 35 PSI. And my mistake, the replacement tire is the Carlisle is the Sport Trail model. Both the original and replacement tires are highway rated, 4.80x12". The orignal tires had a recomended cold inflation pressure of 60 PSI. I think the repacement is 90 PSI. The internet is full of advice on dangers of underinflation, but I cannot find a chart recommending less than max PSI based on load weight.

Doc - I would like to drop down to 20-25 PSI range as you suggest, but am cautious because of all the dangers of underinflation. The mechanic at the tire shop asked me what PSI I wanted on the new tires. I told him 35 PSI. The boss piped in that it should be no lower than 50 PSI. When I got home I found them at 45 PSI, probably a compromise. I hate to wait until there is a pathologic wear pattern in order to diagnose an incorrect guess on pressure, and then have to buy another new set of tires!


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PostPosted: Mon Oct 14, 2013 6:40 am 
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Jim_MI....since your tires wore out in the middle, that is the "classic over inflation" wear pattern....just like a over inflated balloon.
Tires are rated so you do not over load them......as I indicated earlier, my tires have a max load rating of 509 pounds when inflated to 60 psi.
If you inflate your tires to 35 psi, the tires will be "less oval shaped" as compared to the 60 psi inflation.
So, your load is no where close to the max rating of the tires.....as mine are too.
Regardless of the max psi rating, you need to consider how much the actual load the tires are supporting and inflate the tires accordingly.

You could always find a public scale and weigh your loaded trailer.

I know my Hobie Trailex trailer is 160#'s including spare and winch + PA-14 of 175#'s (loaded) = 335#'s total......and tire inflation is 14 psi.
I have not experienced and over heated tires after 70 mph speeds, excessive wear (would appear on the outer edges of the tires) or tire failure.

I would guess your HF trailer is less than 450#'s total loaded weight......so, if it were my trailer, I would run no more than 25 psi and see how it works.
Another benefit of matching the load to tire inflation is a better, less bouncy ride on the road.

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Hood River, OR


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PostPosted: Mon Oct 14, 2013 7:22 am 
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Jim,
The key indicator here is "less than 500 miles" and it wore the tires out. You could almost literally see the rubber coming off them at the rate. I really would check alignment and then get the pressure right. They don't need the 60# max but that shouldn't have worn them out that quickly. Could simply be the HF tires but I would still take the time to check the alignment with your experience in hand. Did the HF tires have a Load Range on them? Wondering if they were for highway use?

Here's an example for some trailer tires I have on a travel trailer. Website: http://www.maxxis.com/Industrial/Traile ... Chart.aspx Click the red link to the PDF. Notice the Load Range is indicated and variation in load and pressure. This is a regulatory requirement that tires for highway use have these load ranges specified on them.

I have a Trailex trailer that carries two PAs side by side. The tires that came on it are 4.80-8 Load Range B . This means a max air pressure of 60 psi which gets you 590 lbs capacity per tire. The Trailex trailer, per regulatory requirements, has a sticker on it specifying inflation pressure at 25 psi. This means they were in no way planning for the trailer to weigh 1180 pounds. I do not have the Load Range chart for the tires and since it carries two PAs, I put 35 to 40 pounds in them. I have several hundred miles on them and they look like new. I carry a spare and remember putting 45 psi in it. The Trailex comes with a very nice axle and I made sure it was perpendicular to the axis of the trailer (i.e. alignment) when I assembled it. I did not fret over toe in/out because the axle appears to be outstanding quality as expected as part of the big price you pay for a Trailex.

Are the new Carlisles highway rated (i.e. Load Range B)?

.

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Alan
2012 PA14 Papaya
2014 PA14 Dune

"If you must choose between two evils, pick the one you've never tried before!"


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PostPosted: Mon Oct 14, 2013 7:26 am 
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The trailer and tire manufacturer's suggestion inflation pressure has a lot to do with the expected load you have on the trailer. A trailer tire inflated to only 15lbs isn't necessarily under-inflated if you are only carrying a very light load on the trailer. The trailer I pull my AI on has tires that are inflated to only 12 lbs. They haven't worn to any noticeable degree and don't get hot after long miles on the highway. But they're only carrying a couple hundred pounds, tops. If I were loading the trailer down with 500 to 1000 pounds, then I'd certainly want to run more pressure in the tires.


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PostPosted: Mon Oct 14, 2013 8:47 pm 
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To the best of my knowledge, Carlisle does not publish a load-inflation chart for this tire. At several places on their website they make a point of saying that there is no advantage to running less than the maximum PSI (which is 90 for the new tires!) I suspect that this is just CYA, since other manufacturers load charts would recommend much lower PSI, probably 20-25 PSI for one loaded PA14. The Carlisle is highway rated, C-load class. The original HF tires were highway rated, B-load class. If anyone knows of a generic load-inflation chart for 4.80x12C tires, I'd love to see it.


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