Tire Pressure - MAX vs DATAPLATE

[dcmac214]

A LOT of replies to tire threads recommend running the trailer (and I assume also car/truck/motorhome) at sidewall max psi instead of the dataplate psi. Why?

My trailer tires have a max psi of 120. The trailer dataplate tells me the correct psi is 80. So I follow the manufacturer recommendation 80psi. I figure they know better than anone else what's 'right' for my trailer.

What benefit(s) would I get running sidewall max 120psi?

Same with my car & truck. Dataplate psi is about half the sidewall max. There may be a noticeable savings in fuel mpg running tires at sidewall max but the ride would probably be so hard as to be quite uncomfortable and I would assume tread wear would be much quicker. And I'd also assume there would be problems with the tire maker if I tried to make a warranty claim while running sidewall max instead of vehicle dataplate psi.

[JIMNLIN]

myredracer wrote:
120 psi?? What is the tire designation on the trailer tires and brand? Big difference in what to do between tire types and what they're on. Are the tires presently on the trailer the same as what's on the placard? They can be different and if run too low, serious damage from heat can occur.

Go to RV tire safety dot com and read about ST tire inflation from a tire engineer.

Good point and good recommendation for those that are clueless about ply shear on close spaced axles on our conventional trailers vs tires on a car/jeep/suv/truck/etc. Apples vs oranges.

The OP is probably out camping and enjoying his trailer....so when he gets back maybe he can clear up the 80 psi placard with 120 psi rated tires.

[Cummins12V98]

JaredWPhillips wrote:
I don't go by the data plate. They put those specs on there based on the factory tires. My Silverado 1500 comes with P-rated tires, 35 PSI.
I actually WORK with my truck, and I have Load-Range-E tires with with an 80psi rating. I keep them at 55. I always tell the tire guys doing the rotation to stop letting the air out of my tires and leave them at 55 where I keep them.

If factories actually put decent tires on vehicles and trailers to begin with, they would have to modify their data plates to show that. But just like my truck, RV manufacturers get away with using the cheapest tire possible. I always go by the specs of the tire you're actually using
and not by the sticker on the vehicle.

Smart Man! Your tires will last twice as long and be much more stable if towing.

[Cummins12V98]

rhagfo wrote:
:Ru
Here we go again :S

I inflate tire both TV and the 5er based on load charts!
I run the LT's on the 5er at 70psi and TV front at 60 and rear 45 to 70 based on load.
It is all about TRACTION! I want the best footprint for the best traction to start, stop, and turn!

YES!!!

As to this scrubbing people get all twisted about. The more weight the tires have on them the more pressure is applied to the tire. The less weight the less pressure is applied. HMMM maybe those tire engineers may know what they are talking about when it comes to load/inflation charts.

So you MAX inflation guys. My 02 Avion platinum had GY "E" tires from the factory and needed 75-80 psi for proper inflation based on weight and the RV mfg said to run 80 and I did. I upgraded to GY "G" that have a MAX pressure of 110psi. Should have I ran 110psi??????????

[mowermech]

Anytime I see this issue, I refer to the Jeep Wrangler Rubicon Unlimited I once had.
The tire data plate said inflate to 33 PSI for max GAWR.
The original tires, installed at the factory, were Load Range E, with a max sidewall pressure (for maximum load) of 80 PSI.
So, apparently, some guys are saying that I should have inflated the tires to 80 PSI, even though there was no way the Jeep would EVER be loaded to over 3000 lbs. per tire.
Actually, I ran those tires at pressures as low as 12 PSI when off-roading.
I never inflated them to more than 33 PSI, as recommended by Jeep.

There is no way I would EVER inflate the tires on the Southwind to the max pressure shown on the side wall. The thing would ride like a logging truck!
I follow the vehicle manufacturer's inflation recommendations.
YOU, of course, are free to do what you want with YOUR tires!

[JaredWPhillips]

I don't go by the data plate. They put those specs on there based on the factory tires. My Silverado 1500 comes with P-rated tires, 35 PSI.
I actually WORK with my truck, and I have Load-Range-E tires with with an 80psi rating. I keep them at 55. I always tell the tire guys doing the rotation to stop letting the air out of my tires and leave them at 55 where I keep them.

If factories actually put decent tires on vehicles and trailers to begin with, they would have to modify their data plates to show that. But just like my truck, RV manufacturers get away with using the cheapest tire possible. I always go by the specs of the tire you're actually using
and not by the sticker on the vehicle.

[rhagfo]

:Ru
Here we go again :S

I inflate tire both TV and the 5er based on load charts!
I run the LT's on the 5er at 70psi and TV front at 60 and rear 45 to 70 based on load.
It is all about TRACTION! I want the best footprint for the best traction to start, stop, and turn!

[Old-Biscuit]

tsetsaf wrote:
OP is clearly running h-rated tires while the placard is for E rated tires.

Exactly........


Placard will also state what size tires psi is for (OEM Tires)

[tsetsaf]

OP is clearly running h-rated tires while the placard is for E rated tires.

[fj12ryder]

Dr Quick wrote:
In 55 years of working on vehicles and trailers, I have NEVER seen a tire fail yet that was inflated to vehicle/trailer MFG. recommended pressure. ...

Seriously? I've had 2 fail in a very short period of time.

[Dr_Quick]

In 55 years of working on vehicles and trailers, I have NEVER seen a tire fail yet that was inflated to vehicle/trailer MFG. recommended pressure. If tire is over inflated by 50%, it will wear more in the center, and there will be less "Foot Print" of the tire in contact with the road. So in an emergency stopping situation you will have maybe 1/3 less grip to stop your trailer. Also ride of trailer will be a lot more harsh.

[the_bear_II]

kellertx5er- wrote
"Sorry, but this is not much of an example. You failed to give any facts which support the decision to inflate to max PSI. It only seems that load range C tires were not suitable for the job. "

------------------------------------------------------------------------
The examples I gave were to illustrate that the dataplates are for original equipment tires. Sometimes the tires get upgraded so the dataplate info may be incorrect.

I also included the suggestion to use the manufacturer's website to determine the correct pressure for the load.

[jadatis]

To my conclusion the sheer forces are not the reason why the tires damage, if the stucture is undamaged that is.
The damage of the structure of the rubber of the tire is courced by to high temperature at critical rings of the tire , the tire produces more heat that can be cooled down , by to much deflection ,or better bending of the rubber,times number of cycles the tire makes a second.

Especially ST tires are calculated in their maximum load for more deflection allowed at the lower speed of 65m/h.
Asuming this calculation is right done, then still its to the edges.
If then some overloading on a tire, or lower pressure cold( misreading of scale or inacurate device) and the deflection gets to much so to much heat production and temperature of the critical rings gets to high and rubber hardens , and at next bendings , so deflections cracks .

Then when sheer forces , even at the lower speeds they happen, these cracks tear the tire apart.

Best is to give the ST tire a pressure of the given pressure of tire, to build in some reserve so it wont get to hot. Even the 10 psi higher or for truck tire 20 psi for 75 m/h can be needed , even if you keep yourselfes below 65 psi.

for your normal car the 51 psi is the maximum cold pressure and not the pressure needed for the maximum load , this is for P tires always 35 psi ( american TRA system), and there they are calculated for 99m/h the deflection. Because you probably never drive this speed, so for normal cars the pressure can be lower then max given.

[DSDP_Don]

"JIMNLIN"....gave a GREAT answer as to why trailer tires should be run at max pressure!

[kellertx5er]

the bear II wrote:
Here's an example:

The company I work for has a fleet of vehicles we can use when going out in the field. One is a chevy 2500 long bed extended cab. Originally from the factory it came with load range c tires with a max PSI of 35. That's what the data plate shows on the door. When the tires were torn up on a rocky road, they were replaced with Load Range D tires. The sidewall shows max is 80 PSI

Similar with a Jeep Cherokee. The tires were replaced with a higher load range tire.

That being said many tire manufacturers on their websites provide charts which indicate the acceptable PSI based on the actual load.

I always keep my tires inflated to the Max PSI indicated on the sidewall. I don't have the time to adjust the pressure depending on load I'm carrying.

Sorry, but this is not much of an example. You failed to give any facts which support the decision to inflate to max PSI. It only seems that load range C tires were not suitable for the job.