Should tires turn freely or have resistance?

[jinx10000]

96 Geo metro lsi 3 cylinder 5 speed
When I turn my back tires and let them go they will keep turning freely. When I do the same with my front tires they stop turning almost immediately. Is that bad? The reason I'm asking is because I only get about 34 mpg highway and I've seen that I should get about 10 additional mpg or more out of the car. I'm also getting pretty loud hum from the front. Time for bearings probably.

[geozukigti]

Your front wheels will never turn completely freely. They are turning gears inside the transmission when you spin them. If you have a hum in the front, you could very well have a bad wheel bearing. Poor mpg can also be caused by bad o2 sensors. OBD-II is very sensitive to bad sensors. You'll probably never see, or rarely see the 40+mpg mark on an OBD-II car though. OBD-II is quite a pig. Your MPG also depends on how fast do you drive at "highway" speed. Your peak MPG will be at between 50 and 60mph. Anything higher and you'll start losing gas mileage.

Gas mileage has a LOT of factors. Tire pressure, type of tires you use, health of the engine and engine components, type of oil you use, driving style, quality of fuel, road conditions, road surface type, air temperature...

EDIT: To better figure out which one of the wheels has a bearing problem, get both front wheels off the ground, put the trans in neutral, and see which one makes more noise when you spin it. With both tires off the ground, it will just be spinning the spider gears in the differential, not the whole trans. The other tire will spin in the opposite direction too.

[unbe]

GeoZuk,
What do you think the average mpg's on an OBDII ,doing most of its driving on the freeway?How would that compare to earlier model?Thanks
Unbe

[jinx10000]

Couple questions. What exactly is OBD-II? Can it be changed out for something else without a big pain in the butt? Can you check O2 sensors and are they expensive.

[geozukigti]

Well, you can see the EPA eat at gas mileage every couple years..
89 Metro
MPG (city) 53
MPG (highway) 58
MPG (combined) 55

1990 metro
MPG (city) 46
MPG (highway) 50
MPG (combined) 47

1991 metro
MPG (city) 41
MPG (highway) 46
MPG (combined) 43

92-94 metro
MPG (city) 36
MPG (highway) 39
MPG (combined) 37

1995(pre-OBD-II)
MPG (city) 44
MPG (highway) 49
MPG (combined) 46

1996 (OBD-II)
MPG (city) 30
MPG (highway) 34
MPG (combined) 32

http://www.fueleconomy.gov

[geozukigti]

Originally Posted by jinx10000

Couple questions. What exactly is OBD-II? Can it be changed out for something else without a big pain in the butt? Can you check O2 sensors and are they expensive.

What is OBD-II? http://en.wikipedia.org/wiki/OBD-II

No, it cannot be changed out without downgrading to a pre-OBD-II electrical system(BIG pain in the butt)

I don't know of any way to check o2 sensors, and yes, they're expensive.. About $80/each.
https://www.automedicsupply.com/cata...66013a31322023

[BeoWolfe]

3 cyl manual trans

OBDII (1996 Geo)

MPG (city) 44
MPG (highway) 49
MPG (combined) 46

Pre OBD II (1995)
Fuel Type Regular Gasoline
MPG (city) 44
MPG (highway) 49
MPG (combined) 46

This is from the http://www.fueleconomy.gov


Greetings,

Geozuk - it appears your list is comprised of some 3 cyl manual specs and some 4 cylinder auto trans specs it is also good to note that the feds have changed how they rate fuel economy every now and then so you can have two of the exact same vehicles built two differnt years and they would be given differnet fuel econ numbers

[DOCTORBILL]

If you don't know how to do it, I'd have some tire place that works on Brakes
and Bearings check out your front wheel bearings.

My '93 3 cyl 5 spd manual Metro coasted like a baby's butt down a greased
slide! 150,000 miles bought used from a private party. Avg 47 mpg...!
On mostly 60 mph country road driving with maybe 25% city driving.

I used to coast down big hills and have to brake!
Nice gas saving feature!

Even with bad front wheel bearings it was a good coaster.

I started hearing loud road noise that I thought was tires. It was tires, but the
noise changed when I turned on a high speed curve. A lot of noise when
turning right, no increase on a left turn.

My Left-Front wheel bearing was quite worn out! A good mechanic can identify
that sound in a shop on a rack.

I replaced mine myself (wouldn't recommend it unless you are a good
mechanic) for $120 each side. Now very very quiet. What a JOB!
Requires special tools and EXPERIENCE.....

Tire road noise - but funny - in fresh snow, so quiet you'd think the engine died!

DoctorBill

[geozukigti]

Originally Posted by BeoWolfe

Geozuk - it appears your list is comprised of some 3 cyl manual specs and some 4 cylinder auto trans specs it is also good to note that the feds have changed how they rate fuel economy every now and then so you can have two of the exact same vehicles built two differnt years and they would be given differnet fuel econ numbers

Oops Thanks. It was late, I guess I got too lazy to read what I googled
My friend's dad does testing for the EPA. Apparently they're drawing up a new style of testing to give consumers a more realistic gas mileage on the window stickers. It's gonna really kill the current CAFE ratings apparently. Probably is gonna be like the new HP rating standard. A lot of cars's HP ratings went way down, while others went way up.