I have the 2008 MMH 4WD, and like it a lot. A couple of months ago I was averaging about 32 MPG per tank. Recently the mileage dropped to around 29, and with the cold weather I assumed it was the decline many mention in mileage with fuel changes, cold warmup, etc.

I checked the tires, and the pressure was down to 30 psi from the recommended 35. I added air to 35, and mileage is back up to the 30-31 MPG range. Inflation makes a big difference in economy. If you think the cold weather is the reason for a recent drop, check your tires too.

-Chris.

 

Take it easy on him guys you might also try this

From the FAQ

 

One other thing, if you can find someone that can fill the tires with nitrogen it will help with changes in pressure due to tempeture changes. They are now marketing machines for tire shops that extract nitrogen from the air to fill tires for this reason.

 

Do you want mercy, or no mercy for the method I use to describe why the whole Nitrogen fad is one of the best perpetuated myths in recent years?
( pretty sure this has already been explained somewhere else on this site... )

 

Has anyone tried using narrower tires? They are lighter, have a lower rolling resistance and have less mass to spin up. If tire pressure makes this much difference, narrow tires will make a bigger difference. And they would probably look strange on an SUV!

 

Mercy, mercy

 

Narrow tires with high pressure have the least rolling resistance. A tire just 1.5 inches wide, and with upwards of 80 pounds of pressure, is commonly used for human powered vehicles just for that reason. They are called "bicycles". There's one little problem, though. The high pressure makes for a very small tread-to-pavement contact area, and very little friction. They tend to skid very easily, especially on wet pavement.

As with most things, it is important to be reasonable. There is a reason why Toyota recommends only 35 pounds of pressure in these tires. That reason is called "safety". You can choose to ignore the manufactures advice, and put in more pressure. When safety is at issue, manufactures tend to be conservative.

Just be aware of the trade off you are choosing to make.

 

The short version on Nitrogen in tires is: It is used for other purposes ( it is non-flammable, does not support combustion, and is available in small, high pressure containers which makes them very portable ) in Nascar and in aircraft tires, but it is NOT used because it leaks less than air, or does not heat up as much as air!

#1 it leaks just as much as air ( air is 78% nitrogen after all )
#2 it heats up just as much as air ( air is 78% nitrogen after all )
#3 filters, traps, and dryers that "dry" the nitrogen in nitrogen vessels can also make regular air dry
#4 a tiny bit of moisture inside your tires does not affect anything

My brother, who is a certified commercial aircraft mechanic says they do put nitrogen in aircraft tires, because:
#1 they cannot run an air compressor around jet fuel
#2 a whole lot of high pressure Nitrogen fits into a small container, and jet aircraft tires take a large volume, and the Nitrogen cylinders are portable, and fill the large tires quickly
#3 it can be used in areas without electricity
#4 compressed air supports combustion
#5 nitrogen would actually extinguish a fire
#6 plain air is used in most private aircraft tires
#7 plain air is allowed in commercial tires

Nascar uses Nitrogen for similar reasons:
It comes in high pressure, portable containers
It fills tires in seconds
It does not support combustion when the fuel can is inches away
It can be used to put out a fire in an emergency
It can be used in areas without electricity
It can be used to run the air tools without a compressor "In the Pit"

( Mark pointed out that last one to me. )

 

Our tires at 80 psi have the same footprint as 1.5" tires at 80 psi would have if installed on our car.

 

While that is true theoretically, in practice it isn't true. The contact patch of the tire x the pressure should equal the car weight. The rigidity of the tire carcass affects deformation of the tread on a car tire and some of the weight may be picked up through the sidewall. However, think about what happens to a bicycle tire on a car (theoretically). If an Escape supports 800 lbs per tire, at 80 psi that requires a contact patch of at least 10 square inches. For a bike tire with a 1.5 inch cross section, that would be almost a 7 inch long contact patch - in other words FLAT. My guess (being too lazy to do the math) is that a bike tire would have to be inflated to about 300 psi just to get the rim somewhat off the ground.