Safe Tire Pressure

[BlackAces]

Originally Posted by Inland RV Center, In

The tire maximum rating, is exactly that.

That pressure should be used when you have loaded the tires to the maximum, and not "just because".

Normally, for a moderate load with load range "D" tires, a pressure of 50 to 55 PSI, will get the job done, and the tires will wear evenly, assuming that the running gear has been properly balanced.

Andy

According to the RMA the tires on that trailer would be considered flat at less than 52 psi if the tire placard recommendation is for 65 psi.

The vehicle manufacturer sets those tire pressures, not their representatives.

If dealers would learn more about the regulations and insure that information was passed on to their customers there surely would be less complaints and/or tire failures on RV trailers.

Here is a very useful reference for the scales. It’s from a major tire dealer. It will also tell you to NEVER use less tire pressure than what is found on the tire placard. Kind of a moot point if the tire placard is already recommending the maximum air pressure found on the tire’s sidewall. Best thing to do then is move your cargo around to get a better load distribution to all tires.

http://www.trucktires.com/bridgeston.../WeighForm.pdf

BlackAces

[switz]

I am in the process of acquiring a new TV. The factory installed Michelin LT265/70R17E tires are rated 3,195 pounds @ 80 psi.

The recommended tire pressure on the rear is 70 psi. The rear axle is rated 6,010 and the tire at that pressure is rated 3,005 (x2 = 6010).

The front axle is rated 5,500 pounds. The recommended tire pressure on the front tires is 60 psi. The tire at that pressure is rated 2,760 (x2 = 5,520).

Maximum pressure is not always used.

[slowmover]

Maximum pressure is not always used

TT's are always max pressure. The TV's we use to pull them are still Load vs. Pressure.

[dkottum]

Sure makes it easy when everybody agrees.

doug k

[Ag&Au]

Originally Posted by switz

I am in the process of acquiring a new TV. The factory installed Michelin LT265/70R17E tires are rated 3,195 pounds @ 80 psi.

The recommended tire pressure on the rear is 70 psi. The rear axle is rated 6,010 and the tire at that pressure is rated 3,005 (x2 = 6010).

The front axle is rated 5,500 pounds. The recommended tire pressure on the front tires is 60 psi. The tire at that pressure is rated 2,760 (x2 = 5,520).

Maximum pressure is not always used.

It has been posted many times in several threads lately that you cannot compare the same tires when used on tow vehicles with use on multi axle trailers. These posts include some by more than one tire engineer. Multi axle trailers cause significant sideways forces to be placed on tires when the vehicle turns. This is a fact, in spite of the non engineers who dispute it based on hearsay or "experience". These forces are not applied to tow vehicle tires or to single axle tires to any significant extent. Therefor usage recommendations for truck tires on trucks or SUVs cannot be carried over to the same tires used on multi axle trailers.

Regarding the post that resurrected this thread:

"My 19' Safari Bambi takes ST225/75 R15 D-range tires with a 65 psi max inflation. I have noticed that the center of the tread wears out before the edges, creating a visible depression in as little as 3K miles. Would it be worth it to run the Marathons at 60 psi instead of 65?"

Since I am guessing your trailer is a single axle trailer, lowering the pressure some would seem to me to be a way of curring the uneven wear you are talking about. However, any reduction in pressure will increase the side wall temperature. It is that temperature that will destroy a tire. You must decide if making the wear more even is worth even a slight increase in risk of sidewall failure.

Ken

[BlackAces]

Originally Posted by switz

I am in the process of acquiring a new TV. The factory installed Michelin LT265/70R17E tires are rated 3,195 pounds @ 80 psi.

The recommended tire pressure on the rear is 70 psi. The rear axle is rated 6,010 and the tire at that pressure is rated 3,005 (x2 = 6010).

The front axle is rated 5,500 pounds. The recommended tire pressure on the front tires is 60 psi. The tire at that pressure is rated 2,760 (x2 = 5,520).

Maximum pressure is not always used.

The procedure the vehicle manufacturer uses for setting the recommended tire pressures for your truck tires is much different than setting recommended tire pressures for RV trailers. By DOT regulation your truck tires must be provided with a set amount of load capacity reserves. That process is accomplished by selecting tires that will provide ample load capacity to accomplish the task.

The only reserve load capacity you will receive for your RV trailer tires will be provided by the vehicle manufacturer. As the regulation is currently written you can receive tires rated at 2000# on 4000# certified GAWR axles.

Because ST tires are designed to be operated at 100% of their maximum pressure rating, trailer manufacturers take advantage of that and use as much of the tires load capacity as possible by setting their recommended tire pressures at the maximum amount.

BlackAces