Why is ford recommending that we over inflate our tires.

[Fishwrinkle]

You’re telling me that at 39psi that rides like a wagon with steel wheels along the Oregon trail is supposed to be the best? I’ll take my 30-32psi any day over 39 cuz my ass says it’s better and so does the tread test. Engineers

it’s more about Ford hitting mpg than anything. Why do you think they invented the golf cart button? So it’s easier on the motor and starter?

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[CarGuy]

I go to my local Costco (as a member), air down, and use the self service nitrogen fill.

 

[kpark_67]

"at the maximum load rating"

Less load = less stress on the tire.

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

That is not true and do not take this advice. The load and tire pressure need to match so that the contact patch is even from side to side and consistent to prevent undo wear, overheating and loss of traction. An over inflated tire will bald in the middle because that is where the contact patch is and that also means sometimes drastically less traction because the contact patch is smaller. When you air over you need more weight to make the contact patch correct for HW speeds. Both under and over bad at highway speeds! The number of ply's on your time also determine what that maximum tire pressure can be and, thus, what the maximum weight rating is. I run my 2dr, 2.7 auto at 36 in front and 34 in back. Both within 1lb of nominal and my ride and tire wear are perfect at 30k miles by keeping all 5 rotating.

 

[kpark_67]

You’re telling me that at 39psi that rides like a wagon with steel wheels along the Oregon trail is supposed to be the best? I’ll take my 30-32psi any day over 39 cuz my ass says it’s better and so does the tread test. Engineers

it’s more about Ford hitting mpg than anything. Why do you think they invented the golf cart button? So it’s easier on the motor and starter?

And that is the real reason.

 

[Fishwrinkle]

And that is the real reason.

come on, if you know what you have then ass and tread test come into play. my response was to the last post on the previous pg. i was on mobile and didn't quote. so by your method, you don't do a chalk test? what do you use, a chart or table?

The auto manufacturer chooses the tire pressure in conjunction with the tire manufacturer for best performance and rider comfort in mind. More goes into that tire pressure on the door jam than you think.

 

[Tex]

What pressure do you guys recommend for these tires on my Bronco? I was about to buy a set, but I couldn't find any info on what pressure I should run with them. They look pretty sweet.

https://www.customwheeloffset.com/b.../mickey-thompson-baja-pro-xs-21-58-24lt-tires

 

[kodiakisland]

My combined GVWR x 1.10 (metric safety factor) = 1,650# per tire. Using the ETRTO Metric Inflation table for a stock tire, 113t load index and it will carry 2485# at 35 psi (my door jamb sticker). For a LT Goodyear Territory @ 35 psi, using the TRA inflation table it will carry 2535# at 35 psi. At 40# is will carry 2685#. Plenty to support any GVWR of the Bronco plus some. My guess is that the engineers know many may choose to air down for "off road" so they want the tire to be overrated so that it can still carry the truck's fully loaded GVWR even at low off road pressures. Just a thought.

The increased load recommendation for highway tires is for dynamic loads, not static. I forget what the official number is, something like 1.54 or 1.58 X GVWR (P metric) for factory load requirements. Then it gets fuzzy converting between P metric, ISO, LT, etc.) Weight in motion is not distributed equally between all four tires, like high speed cornering. Your tires have to support the weight they may find themselves in, not just the weight at each corner sitting still. That's why the door jamb sticker has you inflate to a load value approximately 1.5X the GVWR of the vehicle.

I use a 1.6X factor as it's easier math and easier to remember, but I use my actual weight and not GVWR.

The 1.10 metric factor you mention is the reduction in load rating when using a P metric tire in an LT application. Using P metric tires, you must divide the load rating of the tire by 1.1 when used on a truck instead of a car, or any other application where the load requirement call for an LT weight rating.

 

[kodiakisland]

What pressure do you guys recommend for these tires on my Bronco? I was about to buy a set, but I couldn't find any info on what pressure I should run with them. They look pretty sweet.

https://www.customwheeloffset.com/b.../mickey-thompson-baja-pro-xs-21-58-24lt-tires

I imagine you could remove the valve stems and still run them on the Bronco, if you can clear them.

 

[Natethegreat1979]

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

Please don't spread that false narrative, a REAL off road vehicle DOES NOT have a check engine light on!! I've heard this before and it's dangerously wrong, had a buddy get into some serious trouble on the trail with his check engine light on....

 

[zombie]

That is not true and do not take this advice.

Explain where I provided any "advice"?

I'm not suggesting under or overinflating anyone's tires, but I am suggesting that the vehicle manufacturer's engineers likely know what will work safely.

 

[22OBX]

The increased load recommendation for highway tires is for dynamic loads, not static. I forget what the official number is, something like 1.54 or 1.58 X GVWR (P metric) for factory load requirements. Then it gets fuzzy converting between P metric, ISO, LT, etc.) Weight in motion is not distributed equally between all four tires, like high speed cornering. Your tires have to support the weight they may find themselves in, not just the weight at each corner sitting still. That's why the door jamb sticker has you inflate to a load value approximately 1.5X the GVWR of the vehicle.

I use a 1.6X factor as it's easier math and easier to remember, but I use my actual weight and not GVWR.

The 1.10 metric factor you mention is the reduction in load rating when using a P metric tire in an LT application. Using P metric tires, you must divide the load rating of the tire by 1.1 when used on a truck instead of a car, or any other application where the load requirement call for an LT weight rating.

@kodiakisland Great info, thanks for the catch on the 1.10...yes, divide not multiply. There is black art to air pressure and tire ratings and I wasn't aware of the 1.6 dynamic load factor. I was thinking the 1.10 was a Metric ETRTO (which I think my stock tires are as they have no P designation) OR P Metric to LT.

So correcting this....

• My combined Bronco GVWR/4 = 1,480# for ETRTO Metric tire or LT Tire. (If you have P Metric you would need to divide by 1.10).
• Converting to an LT or ETRTO Metric would be 1480# x 1.6 (dynamic load)= 2,368 # per tire @ Bronco Max GVWR
• Using the ETRTO Metric Inflation table for a stock tire, 113t load index and it will carry 2485# at 35 psi (my door jamb sticker) as this is Max Load. If your under GVWR you could air down below 35 psi.
• For a LT Goodyear Territory @ 35 psi, using the TRA inflation table it will carry 2535# at 35 psi. At 40# is will carry 2685#. If you are under GVWR you could air down below 35 psi.

 

[MPN22BroncoOBX]

. Sorry forgot to mention
2021 badlands non squash 2.7 auto. Worst 5k mileage 18.7(winter) best 20.2(spring,summer)

Wow that’s great, I can’t get more than 17.4 MPG on mine. And I’m easy on the gas pedal

 

[Dude1967]

Just avoid the low tire pressure light thingy... All good

 

[USAGUY]

Wow that’s great, I can’t get more than 17.4 MPG on mine. And I’m easy on the gas pedal

. I do drive pretty soft on the throttle. I also add a can of this stuff every 5k. My bother says “it’s the best”, he’s smarter than me (just ask him). Good luck. Oh yeh, I’m in eco mode 90% of the time.

 

[Jsb]

It also depends if you are running C or D rated tires as they have different pressure ratings. Most D have a 65psi max and a C is 50psi max.

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