Using tire air inflation charts vs side wall markings

myredracer wrote:

Matt_Colie wrote:
You can all have this argument all day long, or you can read what a really truly expert on the subject has to say....
Go to Roger Marbel's RV Tire Safety .

Matt

Agree. ^^^ Based on his advice and experience as a tire engineer, I run our LRD tires at max sidewall pressure. I want the most reserve capacity I can get and I want the best handling possible. I check the tire pressure regularly and adjust it if elevation and/or temp. changes enough. One of the best things we have done to our TT is to add shocks - bounce is substantially reduced and handling on highway curves at speeds up to 65mph is excellent.

If lowering the psi based on load tables, I would go to a scale and get the weight on each side of a trailer to see how much it is unbalanced. You want at least 15 percent reserve load capacity and more is better.

To quote Roger Marble, he says "So the best recommendation I can give to trailer owners is to run the inflation molded on the tire sidewall." So I do and have no regrets.

This is probably a lot different for a TT than a MH. As max will definitely impact ride quality and control. If I ran my MH tires at max it would ride like it had bricks for wheels and handle like a greased pig. Still unclear if the OP has a TT or MH. Makes a big difference. I always set any trailer I had to max. There is no dependency for handling like on a steerable vehicle like a MH.

dup. Need a delete post option...

Matt_Colie wrote:
You can all have this argument all day long, or you can read what a really truly expert on the subject has to say....
Go to Roger Marbel's RV Tire Safety .

Matt

Agree. ^^^ Based on his advice and experience as a tire engineer, I run our LRD tires at max sidewall pressure. I want the most reserve capacity I can get and I want the best handling possible. I check the tire pressure regularly and adjust it if elevation and/or temp. changes enough. One of the best things we have done to our TT is to add shocks - bounce is substantially reduced and handling on highway curves at speeds up to 65mph is excellent.

If lowering the psi based on load tables, I would go to a scale and get the weight on each side of a trailer to see how much it is unbalanced. You want at least 15 percent reserve load capacity and more is better.

To quote Roger Marble, he says "So the best recommendation I can give to trailer owners is to run the inflation molded on the tire sidewall." So I do and have no regrets.

BarneyS wrote:

Desert Captain wrote:
The problem with being in the "full psi camp" is that chances are excellent that you are over inflating your tires. Snip...
:C

In fact, I believe just the opposite is true.
I have always run my trailer tires at maximum sidewall pressure and have never had a single tire related problem.

I have two main reasons for doing that.
1. Most trailer tires are just adequate for the load they are carrying. There is usually very little capability to spare. Many manufacturers depend on the trailers tongue weight or pin weight to allow the installed tires to not be overloaded.

2. The higher pressure will make the sidewalls stiffer which helps keep sway down and also helps keep the tire on the rim when doing tight turns that scuffs the tread along the road. This does not happen on single axle trailer but most travel trailers of any size have two or more axles and will scuff the tread when turning. The bigger the spread between the axles, the more scuffing will take place.
Barney

I've always inflated my trailer tires to max and a lot of times 10+. In 35 years only one tire blow. And that was because the tire went flat because of a nail and got hot and came apart. (so it really didn't blow at all)

I also break every rule known to mankind with my tires.
#1 They are cheap tires.
#2 I always run fast; 70+ most of the time.
#3 I travel in VERY hot weather.

People can run what they want, and I will be happy to run my tires at max pressure with no problems for years to come. :)

BarneyS wrote:

rhagfo wrote:
Snip...
X2 to the Captain!
Before you can state just air to Max, you really need to know what your tires are carrying!

You really got to love those that air to the max, without knowing what they weigh, and what the carrying capacity of their tire is at max inflation.
Snip...

I have weighed my trailer several times both on the way to our snowbird site, on the way home and several time in between. I know exactly what it weighs.

My rig came with C rated tires. I run E tires on it and know precisely what the carrying capacity of my tires and axles is.

I stated my reasons for airing to the max. If you disagree that is fine but no need to try to put down those that do not see it your way.:R
Barney

Barney, didn't mean to offend, but Max is just that what is needed for Max load.

Well so you know what you weigh, you also state you went from from "C" rated tires to "E" rated tires, likely at a big gain in carrying capacity. These tires that have a higher carrying capacity are now aired to Max pressure of 80 psi. Without the numbers of the old "C" and new "E" tires, this isn't an exact statement, but unless the "E" tires are carrying at least about 80 to 90 percent of their max capacity, they are technically over inflated. This reduces the contact patch with the road, decreasing traction for both braking and handling.

Just as a follow up to the MAX pressure discussion. I had a neighbor that ran a couple of log trucks. After several years of tires getting cut to shreds and throwing caps he tried airing down his tires form the Max of 110 to 90 psi. He found that his tires lasted much longer, with far fewer rock cuts and he vary seldom lost a cap.

He also had electronic scales on the truck, and ALWAYS carried at MAX GVW of either 80,000# or 105,000# depending on trailer configuration.

rhagfo wrote:
Snip...
X2 to the Captain!
Before you can state just air to Max, you really need to know what your tires are carrying!

You really got to love those that air to the max, without knowing what they weigh, and what the carrying capacity of their tire is at max inflation.
Snip...

I have weighed my trailer several times both on the way to our snowbird site, on the way home and several time in between. I know exactly what it weighs.

My rig came with C rated tires. I run E tires on it and know precisely what the carrying capacity of my tires and axles is.

I stated my reasons for airing to the max. If you disagree that is fine but no need to try to put down those that do not see it your way.:R
Barney

Desert Captain wrote:

BarneyS wrote:

Desert Captain wrote:
The problem with being in the "full psi camp" is that chances are excellent that you are over inflating your tires. Snip...
:C

In fact, I believe just the opposite is true.
I have always run my trailer tires at maximum sidewall pressure and have never had a single tire related problem.

I have two main reasons for doing that.
1. Most trailer tires are just adequate for the load they are carrying. There is usually very little capability to spare. Many manufacturers depend on the trailers tongue weight or pin weight to allow the installed tires to not be overloaded.

2. The higher pressure will make the sidewalls stiffer which helps keep sway down and also helps keep the tire on the rim when doing tight turns that scuffs the tread along the road. This does not happen on single axle trailer but most travel trailers of any size have two or more axles and will scuff the tread when turning. The bigger the spread between the axles, the more scuffing will take place.
Barney

Your first statement is wrong and only proves that you have been lucky. There is no way you can know the proper psi without weighing the rig and consulting the manufacturers load/inflation table.

Your second comment leads me to believe you are foolish if in fact you are running tires that are "just adequate" and compensating for that by inflating them to their max psi. Why not get tires that can actually do the job without being inflated to their Mac psi?

What do you think happens to those tires when your trailer weight is increased? Ever have to drive home with full black and grey tanks due to the dump station bring out of order or just too crowded? Been there done that.

It is never a good idea to operate anything from tires to toilets at its "maximum".

If you want to be safe put on tires that can do the job (without being at their max psi), and then inflate to the proper psi for that job. This is why every tire manufacturer produces inflation/load data.

:C

X2 to the Captain!
Before you can state just air to Max, you really need to know what your tires are carrying!

You really got to love those that air to the max, without knowing what they weigh, and what the carrying capacity of their tire is at max inflation.

I guess we in the NW are lucky, as both Oregon and Washington typically leave weigh station displays on 24/7/365. I weigh from time to time as stuff is added and removed from the 5er. This way I know if tires need more or less pressure, and where I stand on ratings. I like Captain are not worried about coming home with FULL tanks, as I know I am still within capacities. One time there wasn't any line at the dump station, it was just that the rain was falling sideways that day on the coast.

BarneyS wrote:

Desert Captain wrote:
The problem with being in the "full psi camp" is that chances are excellent that you are over inflating your tires. Snip...
:C

In fact, I believe just the opposite is true.
I have always run my trailer tires at maximum sidewall pressure and have never had a single tire related problem.

I have two main reasons for doing that.
1. Most trailer tires are just adequate for the load they are carrying. There is usually very little capability to spare. Many manufacturers depend on the trailers tongue weight or pin weight to allow the installed tires to not be overloaded.

2. The higher pressure will make the sidewalls stiffer which helps keep sway down and also helps keep the tire on the rim when doing tight turns that scuffs the tread along the road. This does not happen on single axle trailer but most travel trailers of any size have two or more axles and will scuff the tread when turning. The bigger the spread between the axles, the more scuffing will take place.
Barney

Your first statement is wrong and only proves that you have been lucky. There is no way you can know the proper psi without weighing the rig and consulting the manufacturers load/inflation table.

Your second comment leads me to believe you are foolish if in fact you are running tires that are "just adequate" and compensating for that by inflating them to their max psi. Why not get tires that can actually do the job without being inflated to their Mac psi?

What do you think happens to those tires when your trailer weight is increased? Ever have to drive home with full black and grey tanks due to the dump station bring out of order or just too crowded? Been there done that.

It is never a good idea to operate anything from tires to toilets at its "maximum".

If you want to be safe put on tires that can do the job (without being at their max psi), and then inflate to the proper psi for that job. This is why every tire manufacturer produces inflation/load data.

:C

I'll assume your talking about a class C since that's the only rig you mention by type.
And imo, there are plenty of variables to consider when deciding what is the right inflation amount for you, but here's my general take on what I do.
Trailer tires I almost always keep at max psi. Little 14-15" c and d load tires need all the help they can get with heat and tire scrub etc. plus I don't drive slow. If the truck will pull my boat or sled trailer at 80 mph, guess how fast I'm getting there?
Heavy trailer tires, my only experience is with tag trailers, equipment trailers etc and those go max psi cause never know what I or someone else might load it up with.
I also don't believe the over inflation tread wear issue is nearly as pronounced on narrow tires.
Vehicle tires are treated completely different for me. I run the pressure needed for the load, conditions, or season. I'll still err on the high side unless more traction is needed in the winter though.
Btw I've never even looked at an inflation table. After a while you get to know what pressures make you, the vehicle and the tires happy for what you're doing with it.
That said, I'm not changing pressures daily and don't freak out if I load the truck up at Homie Depot and drive 30 mi with only 40 psi in the back tires.

Jmo

Does your tire manufacturer have a psi chart based on weight? If so, they would never advocate blindly adjusting to max. Why bother with the load chart? Max is max. Meaning - they are telling you to inflate your tires UP TO that psi and never over. That is the MAX value you can inflate based on the max load they can handle. It's more of a warning than an instruction. But unless you know what weight you are carrying , you have no way of knowing what to safely inflate your tires to. And that is why they provide the chart, and that is why the tire manufacturers themselves tell you NOT to inflate over max, but to adjust psi based on weight. You can debate it all you want, but if the tire manufacturer is telling you to weigh it and adjust based on the chart they provide, not sure how much credence I would give to an opposing argument to blindly adjust to max. Of course many people have no clue what psi they are running anyway.