Tire pressure

[markcee]

I was always curious about the inflation charts. Why would anyone want to use anything but the sidewall max pressure when towing a TT or 5th wheel? As the max pressure gives you the highest load capacity, isn't that the best/safest way to roll...literally?

In reading other forums, the motorhome folks seem to want/need to tweak their pressures based on individual axle weights and perhaps other things, but what point for trailer owners?

[hazmat456]

Originally Posted by markcee

I was always curious about the inflation charts. Why would anyone want to use anything but the sidewall max pressure when towing a TT or 5th wheel? As the max pressure gives you the highest load capacity, isn't that the best/safest way to roll...literally?

In reading other forums, the motorhome folks seem to want/need to tweak their pressures based on individual axle weights and perhaps other things, but what point for trailer owners?

Simple really, proper inflation will give the greatest contact patch. It will improve braking and control temperatures better. Tire life will also greatly improve as you won't wear out the center from overinflation. That last bit doesn't really apply to trailer tires though as they usually dry rot before they wear out. The trailer will also ride better and bounce less as a result.

[Tireman9]

Why are so many RV owners refusing to get even a basic handle on the load on their tires. Load the RV to the expected heaviest and get on a truck scale. Get the weight for each axle. This is not as good as individual tire loading scale reading but its better than a guess.


Consult the Load / Inflation tables for your type tire and find the MINIMUM inflation needed to support your scale weight. Add 10% to that inflation number.


If you refuse to learn the facts then the least you can do is inflate the tires to the number on your certification sticker unless you have changed size or type. You still need to confirm your loading with a trip to a truck scale. DO NOT GUESS your weight.

[sourdough]

Originally Posted by markcee

I was always curious about the inflation charts. Why would anyone want to use anything but the sidewall max pressure when towing a TT or 5th wheel? As the max pressure gives you the highest load capacity, isn't that the best/safest way to roll...literally?

In reading other forums, the motorhome folks seem to want/need to tweak their pressures based on individual axle weights and perhaps other things, but what point for trailer owners?

Mark you are correct. The ST tire carrying an RV should be run at the max pressure/weight shown on the sidewall. Sidewall rating should then be used as it is measured against the RV. I am not a "tire expert" but I do know that deflating ST tires isn't good for them. So what do you do?

You pick your ST tire, for your trailer, based on the weight you want to safely carry. Some espouse you deduct the pin weight, whatever that may be as it moves on every trip, leaving you with a very marginal tire capacity which cannot, and does not, support the normal anomalies encountered on the road.

On any trip I've ever taken there are times that my tires are supporting the entire weight of my trailer PLUS the thrust/push when that hitch is "in the air" and everything is pushed on the tires, especially the rear. IMO your trailer tires should not ever be sized to max at the weight of the trailer minus the pin weight.....that is just "not smart". Others feel differently but then again some like to run "on the edge"....I don't, and won't.

[CWtheMan]

There are different methods for tire inflation on different vehicles. However, ask yourself these questions; why does the USTMA say to never use less tire inflation pressures than what has/was recommended by the vehicle manufacturer? Why does NHTSA say in all of its FMVSS PDFs or other documents that the correct cold inflation pressures for your tires is what is depicted on the vehicle certification label, tire load and inflation placard and in the vehicle owner's manual?

The automotive industry builds to the same FMVSS tire standards as the RV trailer industry. However, there are different values established for the automotive industry leaving them with options above what has been recommended. Those options are seldom, if ever, found on RV trailer certifications.

Many people that write about tires are apprehensive about tire sizes. A few years ago NHTSA cracked-down on tire nomenclature and fully supports the designated size nomenclature. Within the industry, designated tire sizes are shortened to tire size rather than their correct nomenclature, which is designated size. The prefix on all tires that have one (P - LT - ST) are an integral part of a tires designated size.

I must reiterate, tire load inflation charts are not intended to be recommendations. They provide reference to a tire's load capacity at a given cold PSI value.

[jadatis]

Reacted on old list on page 1, but now see page 2.

Here a newer list,but I advice not to use it.
My offer still counts that I can calculate it for you.
Comes to higher pressure, because a safer formula used and a build in max reserve without screws trembling loose.

[BAPotter]

Thank You Tireman9. For many years I labored under the assumption that max pressure was best. Then I learned from trucking industry and a Goodyear Regional manager that I should be using the pressure based on the actual weight I'm carrying. Inflating to Max Pressure may actually be dangerous in tire life and stopping/control ability. https://www.trucknews.com/features/i...ire-pressures/

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

[CWtheMan]

Originally Posted by BAPotter

Thank You Tireman9. For many years I labored under the assumption that max pressure was best. Then I learned from trucking industry and a Goodyear Regional manager that I should be using the pressure based on the actual weight I'm carrying. Inflating to Max Pressure may actually be dangerous in tire life and stopping/control ability. https://www.trucknews.com/features/i...ire-pressures/

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

All tire inflation pressure standards for vehicles built under the guidance FMVSS are found in those standards.

Trucker tire regulations are governed by the FMCSA. Those two types of standards are not applicable to each other.

Tire inflation pressures for the automotive industry differ from tires fitted to RV trailer axles. The automotive industry requires tire inflation pressures to provide a percentage of load capacity reserves. That standard differs with RV trailer tire fitments which are not required to have any mandatory load capacity reserves.

Note: The RVIA recommendation is not supported by government regulation.

Note: Any NHTSA document about tire inflation pressures is going to say; "the correct tire inflation pressures for your vehicle can be found in the vehicle's owner's manual".

[DBax]

Good move getting rid of those Trailer King tires. (just my opinion). I had one blow out on third trip out. I Put on Endurance and have been very happy with them. I run at max psi as stated on sidewall and check on every trip.

2020 Cougar 366RDS
2019 F350 PS 4x4