Tire Pressures

[FastEagle]

Originally Posted by JIMNLIN

Not true at all.
A FMCSA uses the same FMVSS specs and same tire mfg recommendations.
If you have any fed regs for that opinion please post it for our members who have or use commercial vehicles.

FMCSA allows tire inflation to the load being carried.

FMVSS requires the vehicle manufacturer to set the appropriate recommended cold inflation pressures.

Some tire manufacturers are very uncomfortable about recommending tire inflation pressures for vehicles built to FMVSS standards being inflated for the load carried. In fact, Toyo has a bulletin directed at their retailers disallowing such action.

Variability in tire inflation pressures between what has been recommended by the vehicle manufacturer and what is molded into the tire's sidewall for the tire's maximum load capacity is the green area. Below or above is normally the red area. Inflation to the load carried provides zero room for error with the servicing equipment used to inflate them with. And, of course, there is zero load capacity reserves.

Bottom line; For me, posting tire info is about safety. They don't have to be the bestest, most expensive one's you can find. Properly maintained and not misapplied or abused, most will normally last out to their expected warranty limits.

[JIMNLIN]

Still the same old same old...still no actual fed regs backing up your way out there opinions. Your getting into area you know little about.

The OP has some good information/advice on his P tires pressures from those trying to help.

[FastEagle]

Originally Posted by JIMNLIN

Still the same old same old...still no actual fed regs backing up your way out there opinions. Your getting into area you know little about.

The OP has some good information/advice on his P tires pressures from those trying to help.

I do know this. You can't have it both ways. Industry standards for tire inflation for the automotive industry - excluding commercial standards - is based on the standards used when the recommended cold tire inflation pressures were set by the vehicle manufacturer.

Maybe you should read the information provided in the attached reference.

Readers should know by now that you're posting mostly form a commercial users experience. That information may be good for your goose but not theirs.

https://www.ustires.org/sites/defaul...TruckTires.pdf

[JIMNLIN]

Calvin.... once again your digging yourself deeper and deeper with your off the wall legalistic opinions and clickies to no where.
Hope the OP doesn't get discouraged with his thread being hijacked.

[SmokeyWren]

Originally Posted by FastEagle

Readers should know by now that you're posting mostly form a commercial users experience. That information may be good for your goose but not theirs.

https://www.ustires.org/sites/defaul...TruckTires.pdf

Amen. Jim is an experienced trucker, and he insists that anything that doesn't apply to a commercial truck is not a legitimate concern. For example he doesn't recognize that the GVWR (and the resulting payload capacity) of a tow vehicle is a weight limit, even though every vehicle manufacturer states that the GVWR should never be exceeded.

But the link you posted of the current U.S. Tire Manufacturers Assn (USTMA) publication shows that the USTMA had bowed down to the lawyers fear of lawsuits. They now state the following:

Originally Posted by USTMA

The recommended inflation pressures for tires are typically
measured in pounds per square inch (psi) and are indicated on the vehicle tire placard, certification label or in the owner’s manual. Never set tire inflation pressures below the recommended inflation pressure found on the vehicle...
...
Use of the tires, wheels, and inflation pressures as specified on the vehicle tire placard, certification label or in the service manual ensures that these components can carry the maximum rated axle loads (GAWR) and maximum vehicle weight (GVWR), and also maintains other performance characteristics, if any, intended by the vehicle manufacturer.

So when you pump up your tires on your pickup to the PSI on the placard/sticker, you can haul up to the GVWR and GAWRs of the pickup without overloading the tires. But when driving around unloaded, your tires are overinflated and cause a rougher ride plus wear out the center of the tread.

The answer is to back up a few years and use the method the USMTA required before the lawyers decided to protect the tire manufacturers from lawsuits. That method is to use the load/inflation table for that tire. The load/inflation tables are produced by a bunch of engineers called the Tire and Rim Assn, (TRA). You can rely on those tables to match the max load a tire can support based on the cold inflation (PSI) in the tire. The tables have a minimum PSI that is usually much lower than the PSI on the vehicle sticker. So you can safely reduce PSI to 45 or 50 PSI on an LT tire with 65 PSI max inflation with no worry, as long as you don't exceed the load per the load/inflation table.

USTMA knows this, and they bless the use of TRA load inflation tables, but that blessing is buried way back deep in their publication. It says:

Originally Posted by USTMA

Inflation pressure recommendations may also be determined based on the tire manufacturer’s specifications (i.e., the TRA load/inflation tables), which define the amount of inflation pressure necessary to carry a given load. These inflation pressures may differ from those found on the vehicle tire placard or certification label.

But the lawyers won't allow them to leave it at that. They immediately add on:

However, never use inflation pressure lower than specified by the vehicle tire placard, certification label or owner’s manual.

So even if you often drive around with an unloaded pickup, the current rules of the tire industry won't allow you to use the load/inflation PSI lower than that required to load the pickup to the GVWR. Ridiculous! So I ignore that "however" and use the full range of the load inflation tables, but maybe increasing the PSI by 5 or 10 PSI in case I want to pick up a cutie when cruising around on a Saturday night.

I understand the reluctance of the tire manufacturers and their assn to rely on the TRA load/inflation tables. Proper tire inflation using those tables requires weighing the truck, and requires more brain cells to rub together to interpret the tables than many owners use. So they wind up overloading the tires and then want to sue the tire manufacturer when they experience blowouts. Then the tire manufacturer diverts those lawsuits to the vehicle manufacturer by stating that you should never inflate your tires to less than that included on the Federal Certification Label (door sticker).

Note that most tire manufacturers no longer publish the load/inflation tables. They're getting harder and harder to find. The original source (the TRA annual report to members) requires you to be a member of TRA, and membership is very expensive. Toyo tires still publishes the whole thing, but it's difficult to find on the Toyo website without the following link:https://toyo-arhxo0vh6d1oh9i0c.stack...s_20170203.pdf

[JIMNLIN]

Amen. Jim is an experienced trucker, and he insists that anything that doesn't apply to a commercial truck is not a legitimate concern. For example he doesn't recognize that the GVWR (and the resulting payload capacity) of a tow vehicle is a weight limit, even though every vehicle manufacturer states that the GVWR should never be exceeded.

Lets be careful Smokey. That statement simply is more of your own personnel opinions and isn't what I've posted on this thread .....or in the past about P tire pressure or any tire pressure/tire replacement thread.
GVWR isn't a topic on this thread.

["007"]

This link section four for RV's looks OK to me and I will be posting in the Tire Inflation Thread when we has another confused RV Owner.
Tire Inflation information produced with the Tireman's he[p for confused members on irv2.

[JIMNLIN]

May not be rocket science or alchemy, but being new to towing, it is something I am not very familiar with. I was having trouble putting together useful information and determining of the information out there what was valid and what was not valid information. Didn't realize it had been beaten to death.

818... Pay attention to the last poster 007 who referenced Tireman9 who is a member on many rv websites. He is a actual tire engineer. His rvtiresafety.net eliminates most internet myth about P or ST or LT tires we see posted so much. Pages and pages of reading on the subject.
RV Tire Safety: Interply Shear.

[FastEagle]

The following link is provided on the internet by one of the foremost leaders in in the tire industry. They participate in all committees that write, rewrite and/or establish tire industry standards. Their membership includes all of the major tire manufacturers.

The entire document is a must read for those that write about tires. Chapter four is all about RV tires. It’s the best information you can get unless you’re a member of the TRA who works hand in glove with the Tire Manufacturer’s Association.

https://www.ustires.org/sites/defaul...TruckTires.pdf

This one is a little more complicated but when properly applied it will give a complete outline for selecting and properly servicing replacement tires.

http://www.tiresafety.com/images/Tir...t%20Manual.pdf

Very few tire manufacturer’s provide this sort of information on the internet. All about inflation charts and their usage.

https://toyo-arhxo0vh6d1oh9i0c.stack...s_20170203.pdf

Another great document from a major manufacturer. Toyo does not support inflating tires to the load carried.

https://www.toyotires.com/safety-info

[kedanie]

Hey FastEagle, how about just one time posting what your personal opinion is rather than all those useless links! Most of that junk is a complete wast of time. How about laws and statutes that would apply in a form that is readily understandable.

Just one time?

Keith

[himandher818]

Thanks everyone. There is a lot of info to go over to fully understand tire and pressures. I have gone over some of it, and with all y'alls comments, I can understand some of what I am reading.

I never guessed that tire pressures could be such a hotly debated topic.

I figure I will be going with the tires in the upper 30's when empty, and upper 40's when towing. At least until understand the ins and outs of all this.

Once again thank you all.