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Originally Posted by +Ruff Rider
In response; so if you inflate your truck tires to the load. How do you know the load? There is no way you know how much unless you weigh every time you go out. Then another thing, you always inflate the trailer tires to max pressure correct yet you have absolutely how much it weighs on any given trip.
Another thing I noticed is some trailers have 7,000 pound axles yet the max load is 16,000 pounds, Now I know 7+7=14,000 so Why do manufactures do this?
As for the pot hole a under inflated tire may sustain the same damage. There is no way of knowing that a fully pressurized tire will blow out hitting a pot hole.
More on air pressure. In your car do you add or remove air because you have fewer people in your car? You do know that cars have a max load also. I bet that you go by the yellow sticker in the door for tire inflation and not some stupid chart. Other wise you would need to weigh everyone and inflate according to load. I bet you didn't know that there is a max load for cars also.
So if the yellow sticker is the towing bible than the tire pressure on that same sticker should be gospel don't you think? Or do we chose that the yellow sticker is just a suggestion and only follow some of it?
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To answer your questions;
I don't know about you but my trailer stays loaded pretty much the same for every trip. Once weighed I know within reason what it's going to weigh. As far as the truck I inflate to recommended cold pressure temps (max pressure on the HD truck) any time I tow. If not I lower it to around 65psi normally. Why? Some mental notes; if you have a passenger car or light truck they come with "P" tires. Note that on the sticker in those vehicles the recommended pressure is less than the max pressure on the tire generally (ie; recommended 44psi vs max of 51 example). I've not read specifically but pretty sure that it is because they are "light" duty vehicles and the expected use is not the same as the HD truck. Now, on all HD trucks I've seen (Ram) the recommended max cold pressure is the same as the max pressure on the sidewall (rear). Why? Again, not seen the documentation but it is an HD truck and assumed to be used for HD "stuff", hence the recommendation for max pressure. Why isn't the front rated for 80psi instead of 65psi? The front weight isn't going to vary much but the rear can be subjected to XXX loads so to err on the side of safety (CYA) they recommend max pressures.
I inflate my trailer tires to max pressure because 1) I've had a blowout and don't want it to happen again. Low pressures and sidewall flex will do that to you, 2)my trailer tows and rides better with them at max pressure.
Your observations on trailer axles vs gvw is correct. What you are missing is the fact that the manufacturer subtracts the tongue/pin weight of the trailer THEN calculates what the axles and tires will be resulting in the kind of numbers you give.
As far as the pothole tire damage; yes, an underinflated tire can sustain damage as well as an overinflated tire. Here's the difference; I've driven millions of miles in all kinds of vehicles, with all kinds of tires with all kinds of pressure in them. I've experimented countless times with hard tires, soft tires and in between. An overinflated tire hitting a jagged pothole will cut; and underinflated tire will more likely split, cut and deflate....that's just the way it is in my experience and I feel confident in my assumption.
As far as passenger cars....I'll bet I knew every question...and answer you posed - this ain't my first rodeo. I no longer drive passenger cars but when I did I actually didn't go by any chart or door sticker. I adjusted pressure dictated by the way the tire hit the pavement as illustrated by a chalk line across the tread. I didn't need to "weigh" the vehicle every time I got in it because I knew enough about my tires, and my load, to know what was going on with the tires.
So the yellow sticker is the bible as far as weights but we choose not to follow the tire pressures? This question is kind of pointless. If you will read the load/weight placard, the owner's manual etc. you will see that they say those weights listed "shall not exceed", "must not exceed" etc. We talk about exceeding those weights - not a soul I've seen says you can't run below them. Tires on the other hand have a "recommended" tire pressure setting on a passenger tire that will be inflated to the expected use of the tire - generally below max rating on the tire. You have the upper limit (max pressure on tire) that they can be inflated to if your load increases and they can be deflated by some measure for other circumstances. I used to run 10-15psi in my offroad tires depending on what I was doing. HD trucks (Ram anyway) lists the max pressure allowed on the tire on the placard for the rear. The only logical explanation is CYA. I certainly don't need that load capability when empty (which is most of the time) and have the common sense to know that - and don't like to be pounded needlessly. Hopefully that helps you out.