FFE Higher Tire Pressure - Test Results for Higher Mileage

I've started this dedicated thread for posting reports from FFE owners who have increased their tire pressure beyond the Ford recommended 38psi level to see if they got any higher mileage/range.
This has been commented on in various other threads, but it would be good to have reports here in this easy to find thread now.
I'm interested if higher tire pressure (up to 45psi) increases mileage/range significantly and if it effects slower surface street travel more/less than freeway travel, also how it effects mileage going up hill vs down hill.

I filled my FFE tires up to 40psi a couple weeks ago but noted no significant increased mileage in that time.
I checked the tires today and they were still at 40psi, so no tire air leaks.
I added more air today to fill all the tires up to 45psi.
I am taking a 50+mile roundtrip (mostly freeway) later today so I will see in the Ford trip log later if it I get any significant better mileage and lower Wh/m average than I have for the same trip I've made several times earlier this month with lower tire pressure.

My FFE was charged up to 100% early this morning using value charging set for 12am-4am on my 240V/30A L2 charge station in my garage.
At this moment the car shows 100% battery charge level and estimated 81mile range.

Inflating tires higher than recommended psi comes with a trade off. Keep in mind that over inflated tires will have reduced contact with the road and reduce traction. In rain/snow condition, you are more susceptible to losing control.

I've been running mine at 42 for several months, no obvious increase in range. I've just increased to 45 but don't expect to see much.

In my case, most driving is on the freeway where air resistance is large compared to rolling resistance. Those driving slower have a better chance of seeing an improvement.

I've been driving at 44psi for at least a month now with no noticeable increase in range (if it's there it's probably in the noise).

At about the same time as me increasing the tire pressure the temps around here dropped (from about 80/60 down to around 50/40--hi/low). This temp drop could have easily masked any range increase as I haven't really noticed a drop on range for the temp drop.

I've been averaging 220 Wh/mi recently after about 500 miles of half freeway, half city driving. But, for those 500 miles, I have kept my tires inflated to 45 PSI. Also during this time, my car has been fully charging with range estimates in the high 80s, normally 90s, and occasionally low 100s.

Before that, I was running 38 PSI (the recommended pressure) and averaging about 250 Wh/mi. Fully charged ranges were more like high 70s, sometimes low 80s.

In both cases, my typical driving scores were in the 80s and low 90s.

So... it's been my experience that the difference between tire inflation pressures of 38 PSI and 45 PSI is about 12% more range, or about 10 miles (at least with my driving patterns).

I installed nitrogen in my tires when i first purchased it, and increased to 40 psi. I drive 60 miles/day, all highway/interstate speeds and average 286 Wh/mi. Unfortunately, I have nothing to compare to since it's been that way since new. Temps are falling now, but I was reading mid 80's to low 90's during the summer.

BOLT said:

I installed nitrogen in my tires when i first purchased it

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Why? Regular air is already mostly nitrogen (80%).

The claim in favor of nitrogen is that it is dry, therefore behaves as a pure gas rather than having varying vapor pressure with changes in temperature. Also, the claim is that the oxygen may cause the rubber to deteriorate faster. And nitrogen will inhibit rusting of steel wheels.

I see no downside in using nitrogen other than the hassle factor. I use plain air.

michael said:

The claim in favor of nitrogen is that it is dry, therefore behaves as a pure gas rather than having varying vapor pressure with changes in temperature. Also, the claim is that the oxygen may cause the rubber to deteriorate faster.

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Found this (composition of air):



So, running pure nitrogen is mainly about "oxygen removal" (water vapor content of air is minimal). The biggest supposed benefit would, then, seen to be the claim that nitrogen keeps your tires from deteriorating. But, since most cars seem to run about just fine on air-filled tires without them falling apart prematurely, the benefit of nitrogen would appear negligible (otherwise, all cars would "need" nitrogen-filled tires). I'd argue that most tires you do see that have failed, have done so simply due to over(ab)use, poor maintenance, or poor quality to begin with... not the fact the owner didn't fill them with nitrogen.

michael said:

And nitrogen will inhibit rusting of steel wheels.

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Wouldn't the people likely to spring for nitrogen have cars with alloy wheels?

michael said:

I see no downside in using nitrogen other than the hassle factor.

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By "hassle", you mean finding somewhere to fill your tires with nitrogen and forking over whatever it costs for the privilege? Not to mention having to return whenever your tire pressure needs to be topped off?

Don't forget that tires also deteriorate due to sun (UV) damage. This really isn't much of an issue in cars, but it is huge for any type of recreational vehicle that is stored for extended periods of time (campers, boat trailers, etc.).

As I understand it, compressed air tends to be near saturation. Those with compressors know that it's necessary to constantly purge water from the outlet. Water, unlike a pure gas, transitions between liquid and gas, so there is disproportionate change in pressure. It's like a steam engine...water has the ability to expand/contract more than dry air due to state change.

I have no idea what kind of wheels someone would buy. Neither does, for example, Costco. That's why they provide nitrogen. Water and oxygen aren't good for anything mechanical.

And yes, the hassle involves initially purging the tire of air, then constantly finding sources of nitrogen for top off.

So, even though there may be some advantages in using nitrogen, I don't bother. But there do seem to be some advantages.

Tire Rack has a writeup for anyone interested....

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191

michael said:

Tire Rack has a writeup for anyone interested....

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191

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And here are some others:

http://www.edmunds.com/car-care/should-you-fill-your-cars-tires-with-nitrogen.html
http://www.consumerreports.org/cro/news/2007/10/tires-nitrogen-air-loss-study/index.htm
http://www.wired.com/2007/10/pump-your-tires/
http://www.thetruthaboutcars.com/2007/10/the-truth-about-filling-your-tires-with-nitrogen/

I had thought about filling my tires with argon (same benefits as nitrogen) from my welder. The cost would be negligible and I could top it off or adjust the pressures whenever I wanted. I haven't done it simply because I don't think the benefits are worth the hassle of plumbing a tire hose to my argon tank. I think it has already been mentioned but the only real advantage is the elimination of pressure swings with temperature due to moisture content.

What would be interesting to see is somebody get four "doughnut" rims and put narrow regular (ie. not temporary use) tires on them that can handle higher pressures, say 60 psi. I'd imagine your stopping distance and wet road traction would be significantly affected, but I guestimate your range could probably break triple digits with conservative driving.

I'm gonna use helium and make my FFE lighter.

WattsUp said:

I'm gonna use helium and make my FFE lighter.

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I think you should try hydrogen and call it a fuel cell.

Humidity varies ALOT. The amount of water vapor in the air will vary with the humidity. Since there are sensitive electronics inside the wheel, designed to be open to the air, any humidity is corrosive to these sensors. I can tell you, as a member of the service community, that aluminum wheels corrode also, especially later in years after multiple tire replacements. This probably has as much to do with using soapy water as a lubricant to install the tires, as how much water vapor is inside the tire, but why not eliminate both? We use a waterless lubricant and offer nitrogen tire inflation. NASA uses nitrogen, Nascar uses nitrogen, Tour-de-France bikes use nitrogen. What do they have in common? Performance!
IMHO: If you want the best performance, use nitrogen.

BOLT said:

IMHO: If you want the best performance, use nitrogen.

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Meh... I've never had any of the issues you mention for having used regular air in my tires.

I also doubt that anybody driving a passenger car is going to notice any difference in performance because their tires are filled with nitrogen.

When I get a space shuttle, I might change my mind.

I'm in the same camp as WattsUp. Two cars had tires from Costco, they fill with Nitrogen for free at Costco. Both cars acted exactly the same way as they did with the previous set of tires using air. When it got cold, they all lost pressure. I never noticed any change in handling or keeping pressure as the tires eventually lost all the nitrogen and were on just air (I quit messing with Costco adding nitrogen to the tires - the guys never used the correct pressure, so I just used my air compressor).

I'd never pay extra for nitrogen.

Those competition uses are on nitrogen because they can get a ton of fills in one container and the nitrogen is dry. Air compressors are a pain in the neck to get dry air and they are bigger than a nitrogen tank (remember - everything goes in a semi trailer from track to track). The gas might be slightly more stable or not change pressure as much when the tires heat up - but it isn't like night and day in your regular car.

Well, since we have nitrogen available in our shop, all of my vehicles, trailers, bikes have it. I have been very happy with the results. I offer the nitrogen inflation to our employees for free, and nearly all of our employees have been using it also. My guess is that if you could get it for free, you would try it also. Here is a link for more information, if you want to know more.

http://www.nitrofill.com/nitrogen-in-tires.aspx