It also keeps the gas from volatilizing i.e., splashing and turning into vapor. If the gas expands into vapor, it will actually trick the nozzle into thinking it's full, thereby making the clicker click too soon, and not having a true full tank of gas.

It also depends on time of day, i.e. temperature.

Of course, when you run oversize tires like me, and don't recalibrate the speedo, you really don't care.

 

true. i towed a 86 vw golf from long beach to the bay area in my stock 4wd truck with a 22re. no issues at all.

 

Exactly....

 

This seemed like an appropriate place to share these tips...my main job in the Air Force is Fuels so i hear it all...in one of the earlier posts there was something about nitrogen in the tires, the good thing about nitrogen instead of air is that it doesnt expand/contract with temp and thats why we use it in our aircraft tires, i have never heard about tires wearing from the inside out tho...and it is pretty sad that my V-6 Surf gets less gas mileage than my V8 Nissan Titan, just doesnt make sense to me...lol well here is a cut and paste out of an email that i got from a buddy of mine that works in California....


Here at the Kinder Morgan Pipeline where I work in San Jose , CA we

deliver about 4 million gallons in a 24-hour period thru the pipeline.

One day is diesel the next day is jet fuel, and gasoline, regular and

premium grades. We have 34-storage tanks here with a total capacity of

16,800,000 gallons.



Only buy or fill up your car or truck in the early morning

when the ground temperature is still cold. Remember that all service stations have

their storage tanks buried below ground. The colder the ground the more

dense the gasoline, when it gets warmer gasoline expands, so buying in

the afternoon or in the evening....your gallon is not exactly a gallon.

In the petroleum business, the specific gravity and the temperature of

the gasoline, diesel and jet fuel, ethanol and other petroleum products

plays an important role. A 1-degree rise in temperature is a big deal

for this business. But the service stations do not have temperature

compensation at the pumps.



When filling up do not squeeze the trigger of the nozzle to a fast

mode. If you look you will see that the trigger has three (3) stages:

low, middle, and high. In slow mode you should be pumping on low speed,

thereby minimizing the vapors that are created while you are pumping. All

hoses at the pump have a vapor return. If you are pumping on the fast

rate, some of the liquid that goes to your tank becomes vapor. Those

vapors are being sucked up and back into the underground storage tank so

you're getting less worth for your money.



One of the most important tips is to fill up when your gas tank is HALF

FULL. The reason for this is, the more gas you have in your tank the

less air occupying its empty space. Gasoline evaporates faster than you

can imagine. Gasoline storage tanks have an internal floating roof. This

roof serves as zero clearance between the gas and the atmosphere, so it

minimizes the evaporation. Unlike service stations, here where I work,

every truck that we load is temperature compensated so that every gallon

is actually the exact amount.



Another reminder, if there is a gasoline truck pumping into the storage

tanks when you stop to buy gas, DO NOT fill up--most likely the gasoline

is being stirred up as the gas is being delivered, and you might pick up

some of the dirt that normally settles on the bottom.



Hope this will help you get the most value for your money.

 

As long as you don't go over the max. inflation psi as marked on the sidewall of the tire you'll have no worries. You may find your ride a little "stiffer" them you're used to and your truck/car will handle differently but it is easy to adjust to.
as for BFG ATs I ran my last set at max press [I was hauling contracting tools/materials all the time] and I got 5yrs and 150000Ks+ out of them.

 

Cool...thanks for that info, aviator.
.

 

Not wanting to be a downer here but.... did you consider the floats are not so accurate in the tank and you cant base your numbers off of going from full to 3/4 a couple of times. It is far more accurate to go further down.

I dont know about the rest of you but every car Ive ever owned, new or old, seems to get great mileage the first half of the tank and worse on the second half. I believe this is a result of the inaccurate float gauge.

While tire pressure is a big contributor a lot of us here have bigger rims and tires and different gears yet still rely on our stock odometer for accurate readings. For example the OP says he was getting about 17 mpg he could be getting much more ,around 20, but wont know because he has 33's and the trip meter is geared wrong as a result.

Bottom line is these vehicles are heavy and high both of which make it hard to be economical.

 

as long as you aren't referrencing the gas tank as your filling point (i.e. basing your gas mileage on how much it takes to go from a half tank to three quarters of a tank), it DOES NOT matter what level your gas gauge is at.

the reason is you are filling the tank every time, to the full point, and if you do the same thing with the nozzle at the pump, it will be pretty darn close to being the same level of fuel, EVERY TIME.

and no Allan, I will have NO part in your shinanigans...

 

First, I do not run 33's on my truck. I run 31's. Second, how do you propose it's not accurate calculating from full to 3/4's? Going down from full to half a tank allows for more evaporation of fuel. You can do want you want, buddy, but I've already seen it enough times on my wife's stationwagon to count this "method" as accurate enough. Remember..if you read my first post, I was poo-pooing all of this at first.

And regardless of that...the stock gauge issue, I'm not even calculating against that. I'm counting the odo against the pump at the station.

But, you still make one valid point. Though, I've known about the gear ratio to mileage to speedo/odo for a long time, I've never calculated the change from stock to that on this vehicle. Mainly because I ran 30's since the day I got it and didn't notice any difference running 31's. And, in the end it does not matter since I'm only trying to get better mileage. If I'm actually getting....oh...say 22mpg's, but the calculations are saying only 17mpg's yet I still gain 2mpg's.....well, I've still gained some mpg's.

Just out of curiosity I thought I should calculate for 31's accurately the other day. Soon enough, though, I'll be going back to 30's so I can run some M/T's instead of A/T's, so it's not real important...but, I'm damn curious.

BTW, I realize the limitations of any vehicle like a 4rnr. So, it's not like I'm trying to get more than what's realistic. Just want to see what is the best I can POSSIBLY get. Nothing wrong with that, eh?

 

Here is some more good info, like i said earlier my main job in the air force is Fuels, and if you pay attention to the news the USAF is the worlds leading consumer of Fuel so we get emails like this all the time...here is some more good tips...Brian


Use the Right Octane


Check your owner's manual to find out what fuel octane rating your car's
engine needs then buy it. Octane has nothing to do with the gasoline's
performance, merely its volatility factor in the combustion chamber. Why do
high-performance vehicles need higher-octane fuel? Because the combustion
chamber environment is much hotter in the performance engine. Using
high-octane fuel reduces pre-ignition in the upper regions of the combustion
chamber, which can damage valves and pistons if allowed to go for long
periods of time. So, resist the urge to buy higher-octane gas for "premium"
performance, unless your car requires it.


Properly Inflated Tires


Keep your tires inflated to the proper levels. Under-inflated tires make it
harder for your car to move down the road, which means your engine uses more
fuel to maintain speed. In fact, a single tire, under inflated by two pounds
per-square-inch (PSI), increases fuel consumption by one percent. Check your
owner's manual or the decal in your car's doorjamb for correct inflation
levels. To illustrate the point, deflate your tires by five PSI and try to
push the car. It's not easy. Now inflate those tires and see how pushing the
car is much easier.


Maintain Your Ride


Make sure that you change the oil and maintain your car's powertrain
according to your owner's manual. This will ensure that your car's engine
will operate at maximum efficiency, thus providing the best fuel economy.
Dirty air filters, old spark plugs and low fluid levels can affect engine
performance and fuel efficiency. By keeping your car in top mechanical
shape, it will run better, last longer, and return better fuel economy.
Follow the manufacturer's maintenance schedule. You can check the air filter
by holding it up to a bright light. If it looks clogged or obviously dirty,
replace it. Keep tabs on the fuel filter, also.


Slow Down!


A car uses more fuel under hard acceleration. So don't race up to red lights
or stop signs, avoid quick "jackrabbit" starts, and don't goose the throttle
to jump into holes in traffic. Avoid high speeds on the highway. As your
speed increases, the aerodynamic drag increases in exponential fashion, so
the engine has to work harder - and use more fuel - to maintain your speed
and move the car through the atmosphere. Driving 62 mph instead of 75 mph
can reduce fuel consumption by as much as 15%.


Go Cruising


Maintaining a constant speed over long distances saves gas. The next time
you drive without cruise engaged, note how your speed creeps up and down.
Constant deceleration, followed by acceleration, uses more fuel. The cruise
control feature keeps your speed constant, saving gas (and maybe a speeding
ticket, too).


Drive Light


Heavier vehicles use more fuel, so clean out unnecessary weight in the
passenger compartment or trunk before you hit the road. Unnecessary weight
is anything you don't need for the current trip. Leave it at home and reload
it when you do. (Just for the record, we never referred to your in-laws as
unnecessary weight. Nice try, though).


Ease Up on the A/C


The air conditioner puts extra load on the engine, forcing more fuel to be
used. On average, a car operating with the air conditioning engaged uses
about 20% more fuel. If it's just too hot to bear without A/C, try to keep
it set at around 75 degrees, and don't blast the air when first getting into
your car on a hot day. Open the windows initially, then close up the windows
and set the air at 75. You'll be surprised at how quickly your car will cool
down once in motion.


Close Your Windows


Wide-open windows, especially at highway speeds, increase aerodynamic drag
and the result is up to a 10% decrease in fuel economy. If you want to have
fresh air coming into the vehicle, run your climate system on "outside air"
and "vent," and crack the window for additional ventilation.


Keep the Tailgate Up


Believe it or not, lowering the tailgate creates turbulence, which makes for
more wind drag, and that makes your truck less fuel efficient at highway
speeds. By leaving the tailgate up, you create a smooth bubble of air in the
bed. Air coming over the cab of the truck sees this as a cover -- and passes
over it, thus improving fuel efficiency.


Avoid Idling


Modern, fuel-injected engines do not need to be warmed up, and unnecessary
idling wastes fuel. If you anticipate being stopped for more than one
minute, shut off the car. Restarting the car uses less fuel than letting it
idle. If you're driving a full hybrid, this is not an issue, because the
gasoline engine automatically shuts down when the car is stopped, and the
accessories - such as the air conditioning, lights, and stereo - operate off
the juice stored in the battery pack. This is also one reason that hybrids
often get better fuel economy in the city than on the highway - the gasoline
engine is shut off when idling in traffic.

 

And those of us without a/c midsummer will keep our windows DOWN!!! <<pant! pant!>>>

Good info!

Using aviator's aforementioned tire pressure example, I aired up to 46 in the rear and 42 in the front. The doorjamb says 35 in the rear and 26 up front, but that giveth poopy mileage and ultimately the front tires wear more unevenly. So, at the last tank I got 22.2mpgs. Not sure....all still just expiramentation. But, interesting to note, nevertheless.

I thought I might also keep track of tread depth wear with the higher press. See how valid that whole idea is and what mitigating factors there may be. Such as, tire size, rim size, vehicle weight, tire rotation frequency, etc.

Hey...who knows where a good gear ratio/speedo calculator is?