Why is ford recommending that we over inflate our tires.

[DBC Offroad]

Tire pressure will increase by 4-5 lbs when the car is driven / the tires are warmed up. So if you are measuring at the tire and then looking at the gauge after you've been driving, that would explain the difference. Or your own gauge may be bad.

I measure them cold. And I’ve tried 3 different brands/types of tire gauges to make sure. My Dash is definitely off.

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[RELEGATION BATTLE]

I run my SAS tires btw. 25-30 psi. Totally changes the game and offers a more supple ride. I don’t care about mpg.

 

[RHeinz]

A real off road car always has at least one check engine light on

Sorry, and with all due respect, I’ll have to call you out on that statement too. Short wheelbase Jeeps….CJ2A’s to CJ5’s are some of the most serious off-road vehicles in their stock form ever built. This was way before Check Engine lights were even thought of.

 

[Calm horse]

I stayed at a holiday Inn express last night! If it looks flat put air in it..if it rides like shit, let air out..

 

[Tricky Dick]

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

You'll just wear out your tire centers really fast, but a lot of these paper thin sidewalls will have holes in them before you get to the wear bars anyway.

 

[gwp]

On the inflation note… is everyone’s tire pressure reading in the dash accurate with the actual pressure in the tires?

My dash reads about 5 psi higher than the actual tire.

Mine is accurate, exact to the pound.

 

[gwp]

On the inflation note… is everyone’s tire pressure reading in the dash accurate with the actual pressure in the tires?

My dash reads about 5 psi higher than the actual tire.

Maybe you’re using desert air. Us Easterners have enough extra water in the air to add the missing 5psi.

 

[AKBronc49]

I'm happy with 35 psi on my stock Sasquatch tires.

My e rated Nokian Hakkapeliitta winter tires I run at 30 psi but hate the low pressure light with a passion.

 

[Bronco1971]

You'll just wear out your tire centers really fast, but a lot of these paper thin sidewalls will have holes in them before you get to the wear bars anyway.

Tire wear is a terrific indicator of how happy the tire is. There's all kinds of useful information that can be gathered from it. As you note, over inflation gives the classic medial line wear. You can also see toe issues, camber issues, caster issues, driving style issues, etc. Hell, you can spot a worn ball joint in tire wear.

I have been running my fronts at the 39 and rears at 37 and have gotten nicely even wear over 12k miles, three rotations. The tread depth is equal across the whole tread surface. I vary pressure front to back because the fronts carry a bit more load than the rear. The added pressure creates more resistance to tire deformation on the heavy end. If you were super anal you could obsess over the fact that each corner weight is different.

 

[Tex]

I have been running my fronts at the 39 and rears at 37 and have gotten nicely even wear over 12k miles, three rotations. The tread depth is equal across the whole tread surface.

At 25K my tires looked concave in the center (still do at 30K), no question it was getting excess wear in the center when running in the 36-38psi range. I dropped them to 34psi to see if the wear would start to even out, but really the damage has already been done. I'd have to run them probably 10psi under for another 10K before I could manage to get them even again, and then by that time I probably won't have much tread to care about, so it's not something I'm really interested in doing. Maybe I'll have a cool drag slick/mud terrain tire

 

[Tricky Dick]

At 25K my tires looked concave in the center (still do at 30K), no question it was getting excess wear in the center when running in the 36-38psi range.

This has been my observation. My Territories are second hand with very low mileage and came with a noticeable dish, and I've spotted it on other Broncos.

 

[Bronco1971]

At 25K my tires looked concave in the center (still do at 30K), no question it was getting excess wear in the center when running in the 36-38psi range. I dropped them to 34psi to see if the wear would start to even out, but really the damage has already been done. I'd have to run them probably 10psi under for another 10K before I could manage to get them even again, and then by that time I probably won't have much tread to care about, so it's not something I'm really interested in doing. Maybe I'll have a cool drag slick/mud terrain tire

It's probably a good bet we have different specs on our trucks. My pressures are working for me, they may not work for others. I have had vehicles eat tires weirdly, so I'm kinda anal about watching the wear regularly.

Probably not a good idea to try using under inflation to balance out wear. As you noted, the damage is done, so at the moment you're chasing a moving target and probably aren't gathering accurate information. There are dirt cheap pyrometers on Amazon. Run it on the freeway for 20 minutes, pull over and measure the temps on each side and the center. That should give you a reasonable idea of where the load is being borne. Do this when the tires are new.

The other thing to keep in mind is that all tires are different, one 35 might like very different pressures from one from another manufacturer. Tires have personality. There are hundreds of books that talk about the use of pneumatic tires.

 

[Tex]

This has been my observation. My Territories are second hand with very low mileage and came with a noticeable dish, and I've spotted it on other Broncos.

For a while I thought it was an optical illusion since the tire is round and the tread is flat, some of the flatter style all terrain tires have a tendency to look like that on top even brand new. I noticed it wasn't an optical illusion when the wear channels started to look uneven between the inner and outer lugs.

It's probably a good bet we have different specs on our trucks. My pressures are working for me, they may not work for others. I have had vehicles eat tires weirdly, so I'm kinda anal about watching the wear regularly.

Probably not a good idea to try using under inflation to balance out wear. As you noted, the damage is done, so at the moment you're chasing a moving target and probably aren't gathering accurate information. There are dirt cheap pyrometers on Amazon. Run it on the freeway for 20 minutes, pull over and measure the temps on each side and the center. That should give you a reasonable idea of where the load is being borne. Do this when the tires are new.

The other thing to keep in mind is that all tires are different, one 35 might like very different pressures from one from another manufacturer. Tires have personality. There are hundreds of books that talk about the use of pneumatic tires.

Mine is probably one of the heavier Broncos out there, even as a 2dr. All the steel and whatnot I've bolted on, I would estimate adds a good 600-800lbs, and I'm pretty sure the weight bias is to the rear with reserve fuel based on what the squat looks like at 10psi.

Yeah, it was just a passing thought anyway. They likely won't be around long enough to wear out, I'll be upgrading to 38-40" tires soon enough. Good idea checking tire temp, I might grab my thermal on the next set and see if there's any telltales. For years I'd been finding the right pressure simply by contact patch wear...air up to max pressure and drive down a caliche road to get the tires nice and chalked up, then drive a few miles on the highway with hard turns, max effort accel/decel, then stop to see if all the tread is dirt free. If the center was clean and the edges were still dirty, drop the pressure down and try it again until you just barely clean the entire tread, and you're set. Check psi and write it on the wheel. The benefit there is you're adjusting each tire individually based on what it will actually see on the road, and none of them ever shared the same pressure. It's not perfect by any means but it gets you close enough that you won't have a bald strip in the middle by the time the rest of the tread is below minimum. Doesn't work on some tires when new, particularly the Milestar Patagonia, as they've intentionally engineered the tires to have a center contact patch with floating outer lugs that aren't meant to contact pavement. Thought that was odd (maybe it's marketing BS) but the reasoning is that the center has smaller quieter lugs while the big lugs outside don't make noise if they don't touch. It's a great idea in theory, except you're going to wear that center patch down and the outer lugs will touch before long anyway.

 

[mlugb6ro]

Has anyone tried the chalk test and what did they find with what bronco and what tires?

 

[HeliPilot]

I measure them cold. And I’ve tried 3 different brands/types of tire gauges to make sure. My Dash is definitely off.

Measuring them cold then looking at your dash will not reflect an accurate reading. Your dash is registering the tire pressure from the last time your tires were rotating, which was when they were hot. Go drive your car a few miles, then measure your tires and compare against your dash readings. Willing to bet that they will be the same.

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