tire pressure for a 13' 20lb max?

[Jim Bennett]

I have used Carlisle, Goodyear and many others. I have always kept them at the maximum pressure rating of the tire. Easy peasy, works greats, and eliminates any worry about loading, short of going over the tires maximum.

[ShelbyM]

Originally Posted by floyd

Of course if you wish to run a few pounds lower than maximum tire pressure on less than a maximum load, you can do so safely.

And how do you arrive at this conclusion when Carlisle specifies that their tires are to be run at max sidewall pressure. It's confusing.

[floyd]

Originally Posted by ShelbyM

Well, I guess I don't get your point. Are you using Carlisles and running a pressure other than what they specify (max on sidewall?)

No I'm not. As stated, I run my "C" rated Carlisles at (max on sidewall) pressure(50PSI)

[ShelbyM]

This is getting pretty circular. Moving on.

[WaltP]

It is confusing, I agree. Maybe misleading even. When I think about the physics of it, Carlisle's recommendation makes sense only in the sense of them practicing CYA.
The idea that the best PSI for a trailer tire is the same no matter what load it has makes no sense at all. EXCEPT...it may be, probably is, true that the minimum tread wear on the tire will occur at the maximum PSI it can safely sustain.
But tread wear is generally not the issue here. I gather that sidewall flexing causes most trailer tire failures. At least that's what is often claimed in these discussions.
So if I have, say, Carlisle Radial Trail, load E tires, pulling 4.000 lbs of trailer and contents, and I run it at the max rating of 80PSI, sidewall flexing is at a safe level.
Suppose the next trip I pull the trailer emptied to 2,500 lb. If I reduce the pressure to 55 PSI, I'm willing to bet there will be less sidewall flexing, and maybe less tread wear as well. And surely a lot less stress on the trailer, frame and contents.

That's my story and I'm sticking to it.

Walt

[floyd]

Originally Posted by ShelbyM

And how do you arrive at this conclusion when Carlisle specifies that their tires are to be run at max sidewall pressure. It's confusing.

In this case I run my Carlisles at max sidewall pressure
,but I wrote the check... so they are no longer their tires!
Radial ST tires of all makes have much in common, their advice reflects a greater difference in corporate policy than in the product itself.
Goodyear does NOT prohibit running at max sidewall pressure.

No one can be always right, but I arrive at my conclusions based on what is now 45 years of common sense experience with tires and "tire experts", in fleet service, personal street service,racetrack service, as well as trailer service of all kinds.
I have tried to answer you without equivocation, I am sorry if you found my responses confusing. My advice to you is to ask your tire salesman and follow his professional advice. Moving on...

[Raspy]

Originally Posted by WaltP

It is confusing, I agree. Maybe misleading even. When I think about the physics of it, Carlisle's recommendation makes sense only in the sense of them practicing CYA.
The idea that the best PSI for a trailer tire is the same no matter what load it has makes no sense at all. EXCEPT...it may be, probably is, true that the minimum tread wear on the tire will occur at the maximum PSI it can safely sustain.
But tread wear is generally not the issue here. I gather that sidewall flexing causes most trailer tire failures. At least that's what is often claimed in these discussions.
So if I have, say, Carlisle Radial Trail, load E tires, pulling 4.000 lbs of trailer and contents, and I run it at the max rating of 80PSI, sidewall flexing is at a safe level.
Suppose the next trip I pull the trailer emptied to 2,500 lb. If I reduce the pressure to 55 PSI, I'm willing to bet there will be less sidewall flexing, and maybe less tread wear as well. And surely a lot less stress on the trailer, frame and contents.

That's my story and I'm sticking to it.

Walt

I agree, and that's why I don't give a lot of credit to the unending mantra that "all trailer tires must be run at max pressure all the time". It just doesn't make sense to me and I have a hard time following such absolute pronouncements with no consideration for other factors. CYA is probably the real reason and that is not a good reason.

I only run truck tires now on my Ollie and don't trust trailer tires. Truck tires on my trucks run at many different pressures depending on the many conditions I encounter and I never have any problems with them that are related to pressure.
Running trailer tires that have a history of popping if not inflated properly, and never being able to arrive at a definitive pressure that matches different conditions, seems like an unnecessary gamble.

[ShelbyM]

Sorry folks, I should have known better.

[Raspy]

Originally Posted by ShelbyM

And how do you arrive at this conclusion when Carlisle specifies that their tires are to be run at max sidewall pressure. It's confusing.

An excellent point. To me it's further evidence that Carlisle tires should not be run if they cannot tolerate varying loads and varying pressures. While running in the hot desert at highway speeds, the pressure will go up another 20 PSI or so and you are not following the manufacturer's absolute rule that they must run at max sidewall pressure as the pressure is way higher. If there is tolerance for a 20 PSI increase, is there no tolerance for a 20 PSI decrease?

The whole argument seems unnecessarily convoluted and an attempt to keep weak tires from failing.

[floyd]

Originally Posted by Raspy

An excellent point. To me it's further evidence that Carlisle tires should not be run if they cannot tolerate varying loads and varying pressures. While running in the hot desert at highway speeds, the pressure will go up another 20 PSI or so and you are not following the manufacturer's absolute rule that they must run at max sidewall pressure as the pressure is way higher. If there is tolerance for a 20 PSI increase, is there no tolerance for a 20 PSI decrease?

The whole argument seems unnecessarily convoluted and an attempt to keep weak tires from failing.

It works!... Taken with a grain of salt!

[Raspy]

Originally Posted by floyd

It works!... Taken with a grain of salt!

Yep. Exactly.

When you take a potential exaggeration with a grain of salt, you end up with the truth. In other words, I only exaggerate in the interest of truth. Tricky part is deciding the size of the grain of salt.

[Borrego Dave]

This topic always seems to go a bit sideways, so, it's under pressure that I have to ask. How many of you have actually had a tire "let go" from the pounds you decided to run? IMHO and 50 years of towing, road hazards are far and away more prevalent.