The specs for camber have a lot to do with the inside wear. Mine were set to -2 degrees, which was within spec, but I reset them to -.75 degrees, also within spec but much closer to vertical. The large amount of negative camber is to help resist roll-over, which Ford is particularly sensitive to for some reason....

 

Good point Carl, I know a few posters said they had to modify more than the adjustments to correct the problem. I wasn't concerned to go that far because the higher tire pressure took care of the inside wear for me. Also, like I said, I corner hard and don't want to be concerned with roll-over either. You are the first besides me that I know of that thought Ford did this for a reason. I'm sure Ford could care less that we change tires much quicker with their camber specs.

GaryG

 

To touch on the effects of air pressure to FE. I just raised my air pressure 6PSI all around and added a K&N air filter. I then did a 200+ mile 98% interstate run. Previously on the same trip the best I got 36MPG, this time I was in the high 39.X MPG range. I have a FWD 08 FEH.

I'm positive, between the filter and the air pressure I picked up the 3MPG as I purposefully tried to control all the other variables that I could. The weather was a about 5deg cooler this trip and I don't know about wind direction, all other driving conditions appeared to be the same. I would guess my average trip speed was in the low to mid 60mph. Posted speed is 70 almost the entire way.

I bow to the masters that are getting better than 40 MPG on Interstate travel with the FEH/MMH. I think I'm quickly running out of hardware tricks and will have to start working harder on my driving techniques.

 

It is a matter of diminishing margin of return.

Moving from 35 psi to 25 psi gives you -3 MPG.
Moving from 35 psi to 45 psi gives you +3 MPG
Moving from 45 psi to 55 psi gives you +2 MPG
Moving from 55 psi to 65 psi gives you +1 MPG
Moving from 65 psi to 75 psi gives you .5 MPG

So mathmatically speaking, best you can gain ( or worst you can lose ) is about 9 MPG. But that is a huge amount IF you did not pay attention and had tires at 25 psi ( still very driveable and "look" normal at 25 psi ).
Tires don't "look" flat until about 10 psi.

Now... that's relative to the rolling resistance of the tire during say, highway driving at steady speed. Now... if that psi boost allows you to coast more in the city, more costing will boost your MPG in city even more. So the extra pressure will give you up to 9 MPG and COMBINED with extra coasting you can get +13 MPG. The potential is there, but like Gary says, you have to do everything else right as well. It takes some work. But you CAN get 2-3 MPG more without any work just by adding 10 psi. So as Nike says "Just Do It!" -John

 

Thanks for the info. I guess my only issue is that you are going over the MAX listed psi. I think you are a smart person and know that the listing on the side of the tires is for safety. But it sounds like both you and Laurie are ignoring this and seeing results in the form of better MPG. I just don't feel comfortable doing this, hence I stay below MAX.

I am guessing here but if you have a tire failure, it probably going to be of the blow out variety. Maybe somebody with some tire expertise can chime in.

One last thing, have you played with the camber (toe in/out) of your vechicle to track with less resistance as well? You will get more tramlining but I am curious if there are any other mods being done here.

 

I think what's happen is there has been a number of hypermilers that have increased their tire pressure and dispelled many of the concerns you have asked about. Two years ago, I would have never increased my tire pressure to sidewall max. When we started seeing a decrease in wear and better handling, we determine the tires had a safety benefit with more pressure. I really don't know about going with 60psi being the safest thing, but I have seen an overall benefit at 50psi in my conditions here in FL.

I did have a flat from an object that put a clean hole in my right front tire a few months ago and it leaked down very normal. There was no object left in the tire. I was at a stoplight when someone next to me said my tire was going flat. I pulled over safely with no other damage to the tire or rim. Called my roadside service and the guy showed me the hole and changed my tire. Goodyear repaired the tire and I use it as a spare. There was no blowout problem when the tire was damaged. I wouldn't ever put max pressure in a repaired tire for safety reasons.

I had the front-end adjusted to spec at my first tire rotation at 5,000 miles. Later saw the inside wear and brought it back to Goodyear to check it again. They said it was still at the Ford spec and Escapes had that problem and it was normal. I haven't changed the camber from spec.

At first, I increased the tire pressure for mileage, but I've seen other benefits. About 10 months ago I took a hard left turn at ~70mph. I'm convinced my FEH would have rolled over if my tires had not been so firm. Instead, I was in a controlled slide to the right till I could straighten out on the road.

I'm not so sure the max pressure on the tire is for safety for all conditions. It may be for snow and ice conditions or extreme heat like in a desert where the tire pressure may expand on a 115F road surface. I think I'm fine in my conditions where my average speed on my SGII tank averages is ~22mph.

GaryG

 

Thanks Gary for that explanation. I feel a lot better now filling my current tires above max pressure, and when my MMH arrives, I will do the same.

 

You are welcome to do so of course.....

One thing to consider.... Accepting as fact that the tires handle better and wear better. *IF* you ever have an accident: a tire blows out for a totally different reason, you loose traction and crash into a pole, etc. Its probably not going to matter if the tire pressure had nothing to do with it. The insurance company will have great lawyers and plenty of ammo to fire at you to say, "Well you were running his tires outside the MAX pressure range, therefore since you were intentionally running the vehicle in a way that contradicts proper operating procedure our company will not cover the claims for the vehicle, your medical costs, or injury liability."

And as to the statement of "how would they know".... well among other things, you've posted it here.

Its up to you to decide if thats much of a risk or not.

 

Has this ever actually happened? Probably not. Sounds like a good show idea for MythBusters. And 50psi when a tire is sidewall rated at 44psi is not grossly different. In fact, 44psi is the rating for a cold, un-loaded tire.

A 44psi cold, un-loaded tire will reach 50psi when hot, and heavily loaded, and this is 100% within the design spec.

"Worry Wort!"

 

Maybe.... but people do crash and do have their tires blow. Its just that in this case, the insurance company would have an "out." And we all know that insurance companies are very fair and forgiving and always just cheerfully pay a claim with no problems.