MacGregorSailors.com

There seems to be a discrepancy about tire pressure.
The plate on the trailer says 50psi however everything I can find (on the Internet) says to inflate to max pressure stamped on the sidewall (cold). My 2008 trailer tires say 65psi on the sidewall and so do the new wheels I bought.

http://www.etrailer.com/faq-trailer-tir ... tions.aspx
http://www.boatus.com/trailerclub/trailer_tires.asp
http://www.boatus.com/trailering/2012/june/tires.asp

So what say you? Is the trailer plate misleading people?


--Russ

Tire pressure is determined by weight on the tires. The Max pressure listed on the sidewalls is for the max weight listed on the tires. In my case, since I am at the upper limit of the weight rating on the tires, I use near max pressure.

The pressure listed on the trailer plate should be for a specific weight. If your boat is heaver then what may be listed on the plate then you should use a higher pressure up to the limit, if necessary.

Overinflated tires tend to wear more in the center of the tread. Since our tires usually never need replaced due to tread wear it probably won't hurt much for the pressure to be higher than normal.

I put my trailer tire pressures on my original steel trailer to the max sidewall pressure of 50 psi,at summer ambient temperature of 75 degrees F.

sidewall info is for max weight which for safety-liability reasons is always recommended regardless of weight for the majority of people who A. are clueless with no mech knowledge whatsoever and B. the lazy who just want to do the easiest method possible,that being said the best handling and best wearing for the tire is to match the tire pressure with the tire load which can take a little ciphering and math.On my set-up with dual axles and load range D 15" tires 65psi for 2550# load I run 45psi which is actually slightly over inflated for safety sakes.I could safely run 37-38 psi with no danger of over heating from sidewall flex,but is very important to be alert and monitor pressures in case you develop a slow leak.Some people are clueless as to what a correctly inflated sidewall should look like,while others without even appearing to be looking at their tires will immediately notice a tire that is 4-5 psi low with just a micro-second glance sideways while walking by.This is the same situation as with batteries,where for the majority of people it is recommended to always replace all batteries at the same time which in reality is a total waste of a good battery,but the majority of persons aren't knowledgable enough to know how to test each battery to determine its state of health,so its much simpler(and profitable)to just replace all of them,since you can ruin a new battery if it is in a circuit with another unhealthy battery.But if you told this to a user that runs 50-100 batteries in a large storage bank they would think you were an idiot,you just need to learn and develop your maintence and tech skills.

raycarlson wrote:sidewall info is for max weight which for safety-liability reasons is always recommended regardless of weight for the majority of people who A. are clueless with no mech knowledge whatsoever and B. the lazy who just want to do the easiest method possible,that being said the best handling and best wearing for the tire is to match the tire pressure with the tire load which can take a little ciphering and math.On my set-up with dual axles and load range D 15" tires 65psi for 2550# load I run 45psi which is actually slightly over inflated for safety sakes.I could safely run 37-38 psi with no danger of over heating from sidewall flex,but is very important to be alert and monitor pressures in case you develop a slow leak.Some people are clueless as to what a correctly inflated sidewall should look like,while others without even ...

Could you explain your math calculations, please?

All's I know is my trailer is ALWAYS at max weight for the tires. Gear, 70hp motor, 24 gals of fuel, this thing is heavy so I will inflate them to tax capacity as specified on the sidewall and call it good.

It's interesting that I have historically kept my tires at 50lbs which is what the trailer plate says, however in less than 1000 miles the tires are wearing uneven. So I now believe I've been running UNDER inflated the whole time.

Actually, Russ, that doesn't look as much like under-inflation as it does too much positive camber (wheel tipped in at top, out at bottom). It would appear that the tire is wearing only on the inner side - had it been under-inflation it would have worn more on both the inner and outer edges of the tire somewhat evenly.

I suspect you have, as I did, a bent axle. The cure for me was to re-arch the main axle (i.e. sticking a jack under the center of the axle (center of boat) and raising it until it bent the axle back to the proper camber).

kmclemore wrote:..I suspect you have, as I did, a bent axle. The cure for me was to re-arch the main axle (i.e. sticking a jack under the center of the axle (center of boat) and raising it until it bent the axle back to the proper camber).

I agree and our axle was bent with the same results. When I added the second axle....



http://purplesagetradingpost.com/sumner ... ds-10.html

...I bent the bent one back straight. Over 5000 miles on it and no unusual tire wear. If someone has a single axle and it bends and you bend it back straight chances are it is going to bend again. Probably not too big a problem if you aren't towing much or far but another good reason to add an axle if you are towing long distance.

Put a 2 foot level on the sidewall (up/down) and see where the bubble is or use an angle finder on it. I also run max tire pressure and pump the tires up on the Suburban when towing,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

This is the torsion axle, not the leaf spring axle.
It is designed to directly carry some part of the boats weight.
To much weight, imho.

Discussions here about the center load bearing of this type axle a few weeks ago.
I am still of the opinion that this axle should not be as heavily loaded at it's center as it comes from the factory.

1/4" spacers (at least) need to be installed under the bunks at the rails, or between the axle mounts and rail bottoms, to take more of the direct boat weight off the axle cross member carpeted bunk.

Let the rails take more of the weight like they are supposed to and quit bending the axle making the tires cast out.
imho.

Hardcrab wrote:This is the torsion axle, not the leaf spring axle.
It is designed to directly carry some part of the boats weight.
To much weight, imho.

Discussions here about the center load bearing of this type axle a few weeks ago.
I am still of the opinion that this axle should not be as heavily loaded at it's center as it comes from the factory.

1/4" spacers (at least) need to be installed under the bunks at the rails, or between the axle mounts and rail bottoms, to take more of the direct boat weight off the axle cross member carpeted bunk.

Let the rails take more of the weight like they are supposed to and quit bending the axle making the tires cast out.
imho.

Interesting. My boat is probably heavily loaded and pushing down on the axle in the center. I'll have to see what it looks like with the boat off with a level as Sumner suggested.
I bought a second axle and new wheels. The new axle is an exact replica of the original from UFP and it has a bow in it. I assumed this was because the center bends with the boat's weight to make it straight. In my case, too much.
With the second axle, I suspect many of these overloading issues will go away.

And as mentioned, it's a torsion bar axle so it's not the same as the axle above.

--Russ

RussMT wrote:...And as mentioned, it's a torsion bar axle so it's not the same as the axle above.

--Russ

If it isn't a straight/axle---leaf spring combo then forget my post .

For those that have conventional, non-torsion bar axles one needs to know which they have, before preceding. Some straight axles can come straight where there is no up or down and can be turned with either side to the front. Some have a bow that needs to be up and some have toe-in and there is a front and back side. Or you can have a combination of the preceding. The one on my teardrop has toe-in and I've run the axle above and below the springs for more or less ground clearance depending on if I'm towing it off-road with the Jeep or on road with my street rod. When I do that I have to turn it around to keep the toe in the front when I turn it over to work with the spring locators.

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

Russ..is that 5 years of wear on those tires? Stop worrying about it, replace them in 2-3 more years, and enjoy your boat....

Catigale wrote:Russ..is that 5 years of wear on those tires? Stop worrying about it, replace them in 2-3 more years, and enjoy your boat....

Well, I bought a second axle that I'm going to install next. I also bought 4 new wheels so they all match. That tire is now my spare and I have another "spare" I need to dispose of.

So I guess my tires are significantly different.. The sidewall says never inflate beyond 32PSI max (which is where they're at).

Also, after three years my hubs are dramatically differently corroded. My STBD hub looks factory, while my port hub is rusted and corroded all over. Still accepts grease just fine, but it's very odd that they've corroded so differently.

Matt..send your make and model of tire stat.

32 pounds can't be right for a Mac. I'm worried you have auto tires on your trailer