Why is ford recommending that we over inflate our tires.

[Moabbob]

On my 315/70/17 Goodyear sidewalls and the Goodyear website the max load rating is at 35psi. Why is Ford putting 39 on the door jam as the required psi? Seems
like they are asking you to over inflate the tires. The load rating at 35 is more than enough for the GVWR of the Bronco.

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[RagnarKon]

The tire sidewall rating is the maximum PSI at the maximum load rating.

The Bronco is no where near the maximum load rating of the tire.

 

[Moabbob]

The tire sidewall rating is the maximum PSI at the maximum load rating.

The Bronco is no where near the maximum load rating of the tire.

And Ford is saying to inflate the tires to 4 PSI above that. Doesn't make sense.

 

[Broncotrax]

And Ford is saying to inflate the tires to 4 PSI above that. Doesn't make sense.

Whenever I am traveling light, I inflate to just above the TPMS to keep the light off. This makes a much more comfortable ride. Rarely will I ever go much more than that. Same with My F-250.
I don't always run max load so why use max load pressure settings. I air up to haul the camper and gear for the adventurous days.

 

[zombie]

And Ford is saying to inflate the tires to 4 PSI above that. Doesn't make sense.

"at the maximum load rating"

Less load = less stress on the tire.

Tires fail more often from being underinflated than overinflated, IMO.

 

[Moabbob]

But the tire is rated for a "maximum" load at 35 PSI putting 39 PSI in it won't increase the maximum load of the tire. All that adding the extra PSI is doing is making the tire less compliant and probably worse handling.

 

[7sKnuckledragger]

I’m guessing they are looking to reduce the rolling resistance to achieve fuel economy. Remember Obama telling us to add air to our tires in 08 to help with fuel prices. EPA is hammering automakers to be more fuel efficient so up the pressure. Drop em to 29-30 and the ride will be more enjoyable. A real off road car always has at least one check engine light on

 

[zombie]

But the tire is rated for a "maximum" load at 35 PSI putting 39 PSI in it won't increase the maximum load of the tire. All that adding the extra PSI is doing is making the tire less compliant and probably worse handling.

If the tire was designed to run at 35psi with a maximum load of 6,000 lbs, for instance, it may be able to run at 39psi with 5,000 (I'm not sure of the particular maximums in this case, that's just an example)

 

[RagnarKon]

But the tire is rated for a "maximum" load at 35 PSI putting 39 PSI in it won't increase the maximum load of the tire. All that adding the extra PSI is doing is making the tire less compliant and probably worse handling.

Okay... trying again...

IF the tire is loaded to its maximum (2,535 lbs), the maximum PSI is 35 PSI. The tire is not loaded to its maximum, it's only loaded to around ~1,400 lbs which is a little over half of its load rating, so you can safely inflate the tire above the maximum PSI.

Regardless... Ford's recommended PSI is largely for fuel economy reasons. So feel free to run pressures lower.

 

[swooshdave]

But the tire is rated for a "maximum" load at 35 PSI putting 39 PSI in it won't increase the maximum load of the tire. All that adding the extra PSI is doing is making the tire less compliant and probably worse handling.

The short answer is that you aren't running at maximum load.

You should be running at vehicle manufacture's recommended pressure which is 39psi.

If that's not clear enough then run whatever you want. The tires are cheap, right?

 

[Moabbob]

I’m guessing they are looking to reduce the rolling resistance to achieve fuel economy. Remember Obama telling us to add air to our tires in 08 to help with fuel prices. EPA is hammering automakers to be more fuel efficient so up the pressure. Drop em to 29-30 and the ride will be more enjoyable. A real off road car always has at least one check engine light on

Been running them at 20 off road. But will try 32

 

[Moabbob]

You don't raise PSi for less load. It's all related to heat buildup in the tires.
for the weight of the Bronco it should be at most 32. I suspect Ford is still stinging from the Explorer roll over under inflation.

 

[Spooled]

Okay... trying again...

IF the tire is loaded to its maximum (2,535 lbs), the maximum PSI is 35 PSI. The tire is not loaded to its maximum, it's only loaded to around ~1,400 lbs which is a little over half of its load rating, so you can safely inflate the tire above the maximum PSI.

Regardless... Ford's recommended PSI is largely for fuel economy reasons. So feel free to run pressures lower.

Well, you tried.

 

[Figmo]

The answer to the question of why Ford is recommending a higher psi is to improve fuel economy.

it will yield a rougher ride, but they know you are already going to be not happy with the economy, so they figure if they can squeeze another one mpg it might keep one or two of you from moaning. .

 

[USAGUY]

I’m a bit of a fuel economist nut. I try to do long range testing (5-10 k miles). Many factors to consider when doing this. I will say running my tires at 39psi has given me my best fuel economy. I really don’t feel a huge ride difference.
Btw we are talking 1mpg.
As a topper, many will disagree…….eco mode does work…..Again we are talking 1 mpg.

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