Trailer tire pressures......

[stvmaier]

Ok Folks... I just bought a time out Dart recently... and I'm wondering where to set the tire pressure... The guy I bought it from said to keep it about 10 - 15 psi, But, the max load on the tire says 90 psi. I realize that I'm not gonna be pushing the "Max Load" of the tire, but thought 10 - 15 sounded awfully low. The tires are "Carlisle USA Trail" tires 4.80-12.

Thanks

[Guest tx2sturgis]

About 15-20 PSI should be about right.

 

[Brake Pad]

mine bounce alittle when empty, but I run 58 LBs in mine 12"

[V7Goose]

Low pressure, like 10-15 lbs, will provide the softest ride and would be sufficient as long as the weight in the trailer did not produce much of a bulge in the sidewall.

 

HOWEVER, some of us do not feel that is the best choice, even though it is an acceptable choice. A much higher pressure, even at the sidewall max, will provide the lowest rolling resistance and the longest tire life on a two wheeled trailer. This is my personal preference.

Goose

Edited October 13, 2010 by V7Goose

[stvmaier]

Thanks for the advice. Seems like opinions vary greatly on this.....

[Guest tx2sturgis]

Opinions will always vary. If facts are what your looking for, do a search for 'Tire Inflation Load Table', or something similar.

 

I've included a few here. Its difficult to find tables that go low enough for the tires we use on our small, and lightly loaded, trailers pulled behind a motorcycle. Going by the charts, a 13 inch tire can be run with only 25PSI and still support almost a half ton of weight, per tire, at highways speeds. The facts are that lightly loaded trailer tires do NOT require the maximum pressure on the sidewall. And it can cause accelerated wear in the center of the tread, loose handling in corners, rough rides for the trailer and cargo, and a 'bouncy' trailer. However, in reality, you probably wont 'hurt' anything by running it at the max, it thats what your inclined to do.

 

I run about 12 PSI on my small cargo trailer, with 8 inch tires, and it is happy as can be.

 

Good luck.

Edited October 13, 2010 by tx2sturgis

[SilvrT]

I ran mine with 25lbs fully loaded ... seemed to ride and handle just fine. Mine are the 8" wheels.

[Motorcycle Mike]

I run 25psi in the 12" tires on my Aluma trailer. Pulls great, doesn't bounce and they look new after 30,000 miles.

[Squidley]

I have run mine at 20 psi and pulled a trailer for better than 30K miles. You are absolutely correct in the fact that opinions will greatly vary on this subject

[stvmaier]

Thanks again everyone. That's why I LOVE being a member of this site!! Always plenty of info out there.

[Dave77459]

Trailer tire pressure threads will supplant the "what oil should I use" thread for entertainment and disagreement. I'm convinced.

[Guest tx2sturgis]

Trailer tire pressure threads will supplant the "what oil should I use" thread for entertainment and disagreement. I'm convinced.

 

Yes.

 

And stay tuned for the NEXT 'oil pressure in your tires' thread!

[kj5ix]

I have both 8 and 12 inch trailers. I set the pressure loaded. I spray a patch of the driveway with water, and pull it across the water and look at the pattern on the ground. If I only see the center tread of a tire I let air out until the whole tread is on the ground, and adjust up just a small tad for extra load. 15 to 25 is normal for these small tires. The max pressure marked on the sides are for max weight also, and I suspect that not many will be pulling a 1500 pound trailer with their bikes,,, This method works for me.

 

On the 600 pound camper with 12 inch tires the pressures are Left 22 right 20 full tread on ground both tires. 18 and 20 for the Piggybacker with 8 inch tires.

[1joeranger]

I pulled a trailer, with new tires, 2 summers ago for about 12~15,000 miles with the tires at maximum psi. As mentioned earlier in this post I had to replace them after that trip since the center tread was gone. I now run about 25psi in the new trailer tires and I am expecting to get a longer life out of these. I like tripod's technique with the water!

[V7Goose]

I pulled a trailer, with new tires, 2 summers ago for about 12~15,000 miles with the tires at maximum psi. As mentioned earlier in this post I had to replace them after that trip since the center tread was gone. I now run about 25psi in the new trailer tires and I am expecting to get a longer life out of these. I like tripod's technique with the water!

You may be expecting a longer tire life from the lower pressure, but you will be much better served by actually finding the source of your problem. Your tires were not worn out from too much pressure - you have an alignment problem.

goose

[stvmaier]

How would an alignment problem wear the center tread off??? An "Alignment" problem, be it toe in or toe out will wear the leading edge tread..... Over-inflation wears the center tread... Correct me if I'm wrong. (i've been wrong before..)

[stvmaier]

I'm not trying to start an arguement... just dont understand the theory...

[V7Goose]

How would an alignment problem wear the center tread off??? An "Alignment" problem, be it toe in or toe out will wear the leading edge tread..... Over-inflation wears the center tread... Correct me if I'm wrong. (i've been wrong before..)

First, I think we can all agree that the only part of a tire that can wear away the rubber is the part that touches the ground.

 

Second, I think we can all agree that car and trailer tires that are over inflated for the load will bulge in the center, meaning that only the center of the tire will touch the road (ALL motorcycle tires are shaped this way, no matter what the pressure).

 

Third might be a little harder to get everyone to agree upon, but the logic is irrefutable if you think about it: misaligned trailer tires will quickly scrub off rubber from ANY PART OF THE TIRE THAT TOUCHES THE ROAD. So if a tire is inflated just enough that the tread face is flat and touches the road all the way across and the tire is misaligned so that it is dragging, ALL of the tread will be scrubbed off quickly, but if the same tire on the same misaligned axle is over inflated so that only the center of the tire is touching, then only the center of the tread will be scrubbed off in the same amount of miles.

 

In the case of a misaligned tire, the fact that the center of the tire is worn bald has almost nothing to do with the over inflation, and EVERYTHING to do with the misalignment.

 

The fourth point is the kicker that ties it all together: properly aligned tires on a lightweight two wheel trailer will last MANY thousands of miles without showing wear. I do not have hard numbers for this, but I would expect a minimum of 50,000 in this application. And I do know from first hand experience that 8" tires on a properly aligned small trailer will not show perceptible wear in 10,000 miles.

 

The last point is probably the most contentious (and it is mostly just a repeat of #4): TIRES ON A LIGHT WEIGHT TWO WHEELED TRAILER WILL HARDLY WEAR AT ALL IF THEY ARE PROPERLY ALIGNED. The best example of this is the thin bicycle-like tires fitted on a Bushtec trailer - you never hear of people complaining about tire wear on this quality-built trailer, but those tires have a very thin contact patch, just like an over-inflated little tire on a cheap trailer. In fact, the higher the air pressure and the thinner the contact patch from a trailer tire, the less rolling resistance the tire will have and LESS wear.

 

So the bottom line is that tires on a motorcycle trailer should never show significant wear in just 15,000 miles. If they do show wear, it is only because they are misaligned. If the tires were overinflated but NOT misaligned, they will not show any significant wear in only 15,000 miles. If they DO show wear, IT IS THE ALIGNMENT THAT CAUSES THIS, NOT THE INFLATION!

Goose

 

One last comment trying for absolute clarity on this point - if you keep small trailer tires at maximum pressure so only the center of the tire is in contact under normal load conditions, then when they eventually do wear out, no matter if it is in 3,000 miles from a defective trailer or 70,000 miles from lots of riding, they WILL only be worn in the center. We all know that, and it is not a problem UNLESS you think the tires should have lasted longer. In that case, reducing the tire pressure will NOT make the new tires last longer, it will simply make them look better when they are worn out in the same number of miles as the first set!!! The ONLY way to make trailer tires last longer is to ensure they are properly balanced, properly aligned and turning with the least resistance. Two-wheeled trailer tires should last almost forever simply because there are no acceleration, braking or steering forces that cause them to rub on the road.

So when someone says that a tire worn only in the center shows that the tire was over inflated, they are correct. But they are NOT correct if they suggest that lowering the pressure will make it last longer. It will simply leave you with a better looking corpse.

 

And if everything else is equal, larger diameter tires will last longer than smaller tires simply because they turn slower and fewer revolutions for the same distance. So any particular point on the tread spends less time in contact with the ground during each mile.

Edited October 14, 2010 by V7Goose

[1joeranger]

Thanks V7Goose, always learn something from you! Now how do I fix this problem? When the yoke was extended we used a framing square and plumb string to align the axle. I felt we got her set fairly perpendicular. What would the tolerance be? And what does V7 stand for anyway?

[Squidley]

Ray,

Dave Zipcode here in Houston had an issue with his and it turned out that the HF trailer he bought had not been welded properly.

Here's a link to the write up that Zipcode did

http://www.venturerider.org/forum/showthread.php?t=51272

It's lengthy, but informative and on the 93rd post you'll see what the deal was with Dave's axle. Give this a shot 1st and then go from there, I'll stick with 20 lbs of air in trailer tires

[V7Goose]

Thanks V7Goose, always learn something from you! Now how do I fix this problem? When the yoke was extended we used a framing square and plumb string to align the axle. I felt we got her set fairly perpendicular. What would the tolerance be? And what does V7 stand for anyway?

That thread Squidley noted above has some good information in it (and an awful lot of pointless bickering). As for how to find the problem, see particularly my writeup in post #46 in that thread.

 

Trailers have a LOT of ways they can be misaligned, and just having the axle square with the hitch is only one of them. The frame needs to be perfectly square, the tongue needs to be perfectly straight and square with the frame, and most importantly, the tires themselves must be perfectly square with the hitch. On many cheap trailers, the wheel spindles, and therefore the tires, are NOT perfectly straight with the axle. That is why I use the method I described that bases all measurements on a straight line from the outside face of the tires. The longer your straight edge for this process, the easier it will be to spot any misalignment.

 

And on an unrelated note, V7 was the model designation of the first Moto Guzzi touring bikes sold in this country back around 1970 (V twin engine, 700cc and 750cc), and a Guzzi is generally called a Goose by those who love them. They dropped the V7 designation when they introduced the 850 Eldorado in '74, so only an old fart would remember it. I still have the first V7 Ambassador I bought back then, and it is still my favorite bike. And I have never found anyone else who beat me to the "V7Goose" userid.

 

Ride safe,

Goose

[stvmaier]

Thanks for the detailed explanation VGoose!!! NOW... I DO "get it". As I was reading your comment I was thinking... "OH YEA!!!" And you were correct in thingking that I was relating it to car tires.... I've been a mechanic for 25+ years.....

Thanks again... well done on the explanation..

[1joeranger]

I choose not to read all 114 posts on that thread! Hated I missed all the fun of that one!!

 

I did read post #46, #93 and about the last five threads! Very informative. Loved the pictures and diagram from Dave, V7Goose's techniques and Squidley's assistance! With this new knowledge I will be using an 8' level and plumb bob to determine my issue.

 

Squidley I'll give you a holler when I locate the problem so you can bring the parts over! It's only 574 miles between us so I'm thinking you can get here over a weekend! Don't worry, Conroe is the only place between us that you have to adhere to the speed limit!

 

Seriously though, is there a way to shim the tires in or out depending on the circumstances. My trailer is second hand and modified! So I'm not going to be able to just exchange parts, even if I knew the manufacturer. I realize I need to uncover the issue but just trying to think ahead!

[Squidley]

Ray,

 

I have done a lot crazier things in my days

Let me know what you come up with as there are a few ways that we can correct issues if they appear. Depending on if you have a garage to work out of, I could shoot over that way. If not you can come over here and we could do the work on a weekend.

[1joeranger]

Brad, I've been looking for an excuse to return to Texas for a visit! Besides my mom has been on my case about visiting her for the last several years or so. She lives in the Hill Country west of Austin. I'd love seeing the A&M campus again. Tentative trip plan is Spring Break next semester so I can bring my daughter, her granddaughter, along! So, if you are so inclined, we could stop by and look over the trailer.