¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. A-FrameCamperForum
  2. Topics

Tire pressure

 

I need someclarity folks:

Getting ready for NAR. I have new (last year) Carlisle load D tires. Towing a ranger 12.? Where the large print on the tire? is 65 max PSI; I just noticed fine print that says never go above 35.?

???? Where should I be????
Simply put please!

Thanks,
Kathy
 

That comment "never exceed 35 psi" is followed by "when mounting the tire".? So that's a restriction observed by the tire shop when popping the bead onto the rim.
 

Ah, thanks. I can't read what's after it, it's too small!
Found a sticker on the back that says 50,or do I go with 65?

On Sat, May 11, 2024, 4:47 PM Steve T via <srtimm=[email protected]> wrote:
That comment "never exceed 35 psi" is followed by "when mounting the tire".? So that's a restriction observed by the tire shop when popping the bead onto the rim.
 

¿ªÔÆÌåÓý

I have the same Carlisle LRD tires on my LXE, inflated to 60#.? ?Dave
 

That's what I did? Thanks Dave.


On Sun, May 12, 2024, 6:45 AM Dave - Webmaster via <dhmwebmaster=[email protected]> wrote:
I have the same Carlisle LRD tires on my LXE, inflated to 60#.? ?Dave
Jean-Francois Larin
 

That is a complex question that is difficult to answer 100% clearly.

The tire must be inflated enough to hold the load without deforming. When deformed (under load) it heats up and explodes (I drove an underinflated tire on an utility trailer for 4 km to get to the service station to inflate the tire. I never got there the tire got destroyed before that.)

Higher is the pressure, higher the tire can be loaded.? But that is up to the max pressure. At that max pressure identified on the sidewall, the tire can safely be loaded with the indicated weight, but no more.? So If you take for example my Ranger 15, it had load range C tires.? It had to be at the highest pressure (50 psi) because the max trailer weight is 3000 lbs, which is distributed on both tires and on the tongue (10% of the load). So the tire were very close to the max load.? Accordingly, when held to 50 PSI, they were slightly overinflated (because I did not actually loaded the trailer to 3000 lbs, amongst other things) and got worn-on in the center.

Here is some image of the results of over vs under inflation:

So when I changed the tire, I changed for load range D tires, which can be inflated up to 65 psi (instead of 50 psi for load range C). Those can take more load, so I have more margin.? Also, even if I don't have a load chart, I know that if I load them with 50 psi, they can hold AT LEAST what a load-range C tire of the same size would hold (that's my general understanding, not something a manufacturer will tell you)? So anything between 50 psi will be valid for my trailer.? If I stand closer to 50 psi, I am close to minimal value where it can overheat and explode. If I am closer to 65 psi, I risk overinflation effect of wearing only the center and it will be a rougher ride, but it will not explode.? So watching the wear on the tire is a good confirmation that I am at the right inflation with enough margins.

It might look strange to change the tire pressure based on load, but if you watch a car tire pressure, you'll see that it is adjusted from car to car to fit the actual car maximal weight.? In fact, I read today the manual for my car and in the trailer section, they specifically mentioned that when towing a trailer, which brings more weight on the axles and tire, I should increase tire pressure of the car/truck up to the maximal pressure marked on the tire to allow it to support more load.

?

So what Dave wrote previously to load it to 60 lbs is a pretty good bet.

jf
 

Another reason to inflate tires to max psi (or close) is doing that makes them less likely to have a blowout.? If the downside of too much psi is center tire wear, and the downside of too little psi is a blowout that can do thousands of dollars in damage, I'll take the center tire wear in a heartbeat. But I've run D tires for 4 years and never saw center tire wear.? With the small 13" wheels the trailer weight is high enough that center tire wear doesn't happen.

So that raises the question of if max psi is best, why not inflate to 65 psi instead of 60?? The answer may contain a bit of reducing center tire wear, and a bit of making the tires ride more smoothly.? But for me, its watching a tire pressure monitor.? I inflated my C rated tires to 50 psi in the morning when its a cool 40 degrees.? I get out on the freeway and the temps go up to 95, and the pressure monitor shows the tires at 60 psi.? I know that the 50 psi max for C tires is cold inflation pressure, and I know the pressure will increase as temps go up, and I know they say that's ok.? But I just don't want to see 60 when the max is 50.? I've talked to others who had the same gut reaction.? So when I got my next set of tires, I switched to D rated, and I've been running those at 60 ever since.


On Sun, May 12, 2024 at 04:58 PM, Jean-Francois Larin wrote:

That is a complex question that is difficult to answer 100% clearly.

The tire must be inflated enough to hold the load without deforming. When deformed (under load) it heats up and explodes (I drove an underinflated tire on an utility trailer for 4 km to get to the service station to inflate the tire. I never got there the tire got destroyed before that.)

Higher is the pressure, higher the tire can be loaded.? But that is up to the max pressure. At that max pressure identified on the sidewall, the tire can safely be loaded with the indicated weight, but no more.? So If you take for example my Ranger 15, it had load range C tires.? It had to be at the highest pressure (50 psi) because the max trailer weight is 3000 lbs, which is distributed on both tires and on the tongue (10% of the load). So the tire were very close to the max load.? Accordingly, when held to 50 PSI, they were slightly overinflated (because I did not actually loaded the trailer to 3000 lbs, amongst other things) and got worn-on in the center.

Here is some image of the results of over vs under inflation:

So when I changed the tire, I changed for load range D tires, which can be inflated up to 65 psi (instead of 50 psi for load range C). Those can take more load, so I have more margin.? Also, even if I don't have a load chart, I know that if I load them with 50 psi, they can hold AT LEAST what a load-range C tire of the same size would hold (that's my general understanding, not something a manufacturer will tell you)? So anything between 50 psi will be valid for my trailer.? If I stand closer to 50 psi, I am close to minimal value where it can overheat and explode. If I am closer to 65 psi, I risk overinflation effect of wearing only the center and it will be a rougher ride, but it will not explode.? So watching the wear on the tire is a good confirmation that I am at the right inflation with enough margins.

It might look strange to change the tire pressure based on load, but if you watch a car tire pressure, you'll see that it is adjusted from car to car to fit the actual car maximal weight.? In fact, I read today the manual for my car and in the trailer section, they specifically mentioned that when towing a trailer, which brings more weight on the axles and tire, I should increase tire pressure of the car/truck up to the maximal pressure marked on the tire to allow it to support more load.

?

So what Dave wrote previously to load it to 60 lbs is a pretty good bet.

jf
 

Ditto. We have GoodYear Endurance tires (rated D) and have been running them at 60 pounds for over two years.
 

I added a TPMS to my camper so I can monitor the pressure increase or decrease.? I did read something that I found useful, but have not yet tried.? Run chalk across the tires, then drive around a bit and see where the cahulk wore off.? That would indicate where the tire is contacting the pavement.

--
Don DeRyke
Sunrise, Florida

2009 Classic, 2020 Ford Escape, 2.0 liter EcoBoost, AWD.?
Previous TV 2015 Ford Escape 1.6 ltr EcoBoost engine.

1 - 9 of 9