Gas Mileage
#31
11-05-2008, 06:32 PM
RE: Gas Mileage
A side note: I just put on new tires a couple of months ago (Cooper Discoverer HT), which are silent compared to the original Contitracs. However, these new Coopers must present more rolling resistance because I immediately lost 1.5-2 mpg as soon as I checked gas mileage. That amounts to $300/year is increased gas costs! (@ $4/gal)
Check Consumer Reports tire ratings for rolling resistance if gas mileage is important to you...if the rating on the tires you want is less than average, beware!
Check Consumer Reports tire ratings for rolling resistance if gas mileage is important to you...if the rating on the tires you want is less than average, beware!
#32
11-06-2008, 08:36 AM
RE: Gas Mileage
Copied from Wikipedia
Low-rolling resistance tires are tires which are designed to improve fuel efficiency of a car by minimizing the energy wasted as heat as the tire rolls down the road. Approximately 5–15% of the fuel consumed by a typical car may be to overcome to rolling resistance.[1] A 2003 California Energy Commission (CEC) preliminary study estimated that adoption of low-rolling resistance tires could save 1.5–4.5% of all gasoline consumption, but that current data were also insufficient to compare safety and other characteristics.[2] A database of much more complete data will be released by the CEC pending completion of an ongoing study.[3]
Based on my interpretation of this, low-roll tires may save an average of 3% over standard tires. For the Tribute, this would translate to something like 3% of 18mpg, or 0.5mpg. If you are using low noise tires, then your rolling resistance is probably fairly low as well. You do not mention any noise or handling issues. Balancing, alignment, etc, could impact mpg. Is there some other factor that would give you the impression of reduced mileage, such as more city driving, measurement error, seasonal switch to oxygenated fuel,etc?
Also copied from Wikipedia
Effects
Rolling friction generates heat and sound energy, as mechanical energy is converted to these forms of energy due to the friction. One of the most common examples of rolling friction is the movement of motor vehicle tires on a roadway, a process which generates sound and heat as by-products.[11] The sound generated by automobile and truck tires as they roll (especially noticeable at highway speeds) is mostly due to the compression (and subsequent decompression) of air temporarily captured within the tire treads. The heat generated raises the temperature of the frictional surface; moreover, this temperature increase typically increases the coefficient of friction itself.[12] This is why automobile racing teams preheat their tires.
Low-rolling resistance tires are tires which are designed to improve fuel efficiency of a car by minimizing the energy wasted as heat as the tire rolls down the road. Approximately 5–15% of the fuel consumed by a typical car may be to overcome to rolling resistance.[1] A 2003 California Energy Commission (CEC) preliminary study estimated that adoption of low-rolling resistance tires could save 1.5–4.5% of all gasoline consumption, but that current data were also insufficient to compare safety and other characteristics.[2] A database of much more complete data will be released by the CEC pending completion of an ongoing study.[3]
Based on my interpretation of this, low-roll tires may save an average of 3% over standard tires. For the Tribute, this would translate to something like 3% of 18mpg, or 0.5mpg. If you are using low noise tires, then your rolling resistance is probably fairly low as well. You do not mention any noise or handling issues. Balancing, alignment, etc, could impact mpg. Is there some other factor that would give you the impression of reduced mileage, such as more city driving, measurement error, seasonal switch to oxygenated fuel,etc?
Also copied from Wikipedia
Effects
Rolling friction generates heat and sound energy, as mechanical energy is converted to these forms of energy due to the friction. One of the most common examples of rolling friction is the movement of motor vehicle tires on a roadway, a process which generates sound and heat as by-products.[11] The sound generated by automobile and truck tires as they roll (especially noticeable at highway speeds) is mostly due to the compression (and subsequent decompression) of air temporarily captured within the tire treads. The heat generated raises the temperature of the frictional surface; moreover, this temperature increase typically increases the coefficient of friction itself.[12] This is why automobile racing teams preheat their tires.
#33
11-06-2008, 07:22 PM
RE: Gas Mileage
Hi Tom,
I had the tires installed in late September. All summer and early fall, I was getting a steady 23-23.5 mpg with the old Contitracs. The next fillup, after running the Coopers for a full tank, that mileage dropped to 21.5. Since, then the mpg has been anywhere from 20.8-21.5 ( I am **** about gas mileage
! There has been no change in my driving habits. Perhaps a little of the drop can be attributed to lower temperatures lately, but that doesn't explain the drop in Sept., which was still pretty warm around here and the Contis were still recording 23 mpg the week before. The Coopers are rated below average for rolling resistance, according to CR. I figured that might contribute to a .5 mpg loss, at the most. Imagine my surprise now that I can't break 22 mpg anymore. I have even stayed at 60 mph instead of 65 mph, and still can't break 22. Not only was 23 mpg common with the old tires, sometimes I would get 24or 25 mpg, 26 on long trips!
I almost spent an additional $200 on Michelins, which were rated above average on rolling resistance. Thinking that rolling resistance wouldn't make that big of a difference, I went with the cheaper Coopers. I will probably make up the $200 I didn't spend on the Michelins in reduced mpg this year alone. Oops.
I am happy with the Coopers, other than the gas mileage. They are very quiet and offer good traction.
I had the tires installed in late September. All summer and early fall, I was getting a steady 23-23.5 mpg with the old Contitracs. The next fillup, after running the Coopers for a full tank, that mileage dropped to 21.5. Since, then the mpg has been anywhere from 20.8-21.5 ( I am **** about gas mileage
! There has been no change in my driving habits. Perhaps a little of the drop can be attributed to lower temperatures lately, but that doesn't explain the drop in Sept., which was still pretty warm around here and the Contis were still recording 23 mpg the week before. The Coopers are rated below average for rolling resistance, according to CR. I figured that might contribute to a .5 mpg loss, at the most. Imagine my surprise now that I can't break 22 mpg anymore. I have even stayed at 60 mph instead of 65 mph, and still can't break 22. Not only was 23 mpg common with the old tires, sometimes I would get 24or 25 mpg, 26 on long trips!I almost spent an additional $200 on Michelins, which were rated above average on rolling resistance. Thinking that rolling resistance wouldn't make that big of a difference, I went with the cheaper Coopers. I will probably make up the $200 I didn't spend on the Michelins in reduced mpg this year alone. Oops.
I am happy with the Coopers, other than the gas mileage. They are very quiet and offer good traction.
#34
11-07-2008, 08:06 AM
RE: Gas Mileage
Wow, you are doing much better than me with your mpg. I am usually below 20 with my 2002 4WD 3.0.This includes a fair amount of highway.Though I have a fair amount of wear left on my tires, I will be more considerate of the rolling res spec and see if I can get an improvement with better tires in the future.
The tires I have now are quiet and have a fairly long wear life (60,000 miles I think). This would lead me to believe that the roll-res should be lower since the compund may be harder to get the longer life. But then again I am not a tire expert.
The tires I have now are quiet and have a fairly long wear life (60,000 miles I think). This would lead me to believe that the roll-res should be lower since the compund may be harder to get the longer life. But then again I am not a tire expert.
#35
11-08-2008, 09:22 AM
RE: Gas Mileage
I am not sure about the relationship between longevity and rolling resistance myself. The Coopers I have are supposed to last about 50K and have high rolling resistance. However, the Michelins I was going to buy had less rolling resistance (according to CR) but people online report getting 80-100K miles out of them.
My gas mileage is probably higher because I live in a rural area and pretty much everywhere I go involves driving on a 55 mph highway. I work 25 miles from home and get there in 28 minutes, if you need proof! I read many posts about people complaining about their Tribute's gas mileage, while I was getting a consistent 23 or more, so I didn't know what they were talking about. Now that I am a victim of rolling resistance and -2 mpg, I am starting to see the limited cruising range and have started complaining myself. The Ford Duratec 3.0 is not a model of efficiency. It's been around since 1995 and has always been more of a gulper than a sipper. I think a lot of the blame belongs to the transmission. They engineered it to shift smoothly, but that also created a lot of slippage which wastes fuel. Also, just a little too much pressure on the gas causes the torque converter to unlock or a downshift to 3rd, even on the slightest hills. If it were geared a little lower and the engine turned 2100 rpm @ 60 mph instead 1900 rpm, maybe some of those downshifts would be eliminated.
My gas mileage is probably higher because I live in a rural area and pretty much everywhere I go involves driving on a 55 mph highway. I work 25 miles from home and get there in 28 minutes, if you need proof! I read many posts about people complaining about their Tribute's gas mileage, while I was getting a consistent 23 or more, so I didn't know what they were talking about. Now that I am a victim of rolling resistance and -2 mpg, I am starting to see the limited cruising range and have started complaining myself. The Ford Duratec 3.0 is not a model of efficiency. It's been around since 1995 and has always been more of a gulper than a sipper. I think a lot of the blame belongs to the transmission. They engineered it to shift smoothly, but that also created a lot of slippage which wastes fuel. Also, just a little too much pressure on the gas causes the torque converter to unlock or a downshift to 3rd, even on the slightest hills. If it were geared a little lower and the engine turned 2100 rpm @ 60 mph instead 1900 rpm, maybe some of those downshifts would be eliminated.
#36
11-12-2008, 09:23 PM
RE: Gas Mileage
I'm now up to 65,000 miles on the Tribute and still seeing an average of about 20mpg. I do the occasional shot of concentrated fuel injector cleaner to keep it up when it starts to lag or drop on me. But my day to day driving ventures have me all over with all types of terrain ie., off road, highway, city and then some. My GPS even shows that my average speed sits about 35-45 mph when I refresh it about once a week. I typically average 100-200 miles per day as I conquer the Western and Central part of Massachusetts one day at a time and back again.[8D]
#37
11-12-2008, 09:27 PM
RE: Gas Mileage
This may want is own post, but I am wondering what people are running for air pressure in their tires so we can compare to mpg that people are experiencing. I know I saw a post earlier today that some folk are saying to run at 44psi as apposed to the 30-33 mark... what do you think?
#38
11-13-2008, 04:08 PM
RE: Gas Mileage
I have had great success with my 2001 4cyl. I have 177,000 miles on it and still get 27 mpg on a mixed trip. I do more hwy than city miles, but have gotten 29.8 mpg on my trib for all highway. I did just have to change the clutch, which finally wore out,... we will see if I continue to get such good milage.
-josh
2001 tribute dx 4cyl, 177k miles
-josh
2001 tribute dx 4cyl, 177k miles
#39
11-13-2008, 05:27 PM
RE: Gas Mileage
I am guessing your 4 cylinder is also a FWD only...AWD will steal 2-3 mpg regardless of the engine due to the additional drivetrain and weight.
Tire pressure...when my crappy ContiTracs were about worn out, I ran them at 35psi each to increase mpg. It worked...a gained about .5 mpg as a result. However, I wouldn't run a decent set of tires above the recommended pressure. It will increase your gas mileage slightly, but may cause the center of the tread to wear quicker than the sides of the tread. Also, it will make the Trib's firm ride even harsher. Most significant is the fact that too much air pressure may change the handling characteristics of a vehicle with a high ground clearance and a short wheelbase...not a safe combination.
Tire pressure...when my crappy ContiTracs were about worn out, I ran them at 35psi each to increase mpg. It worked...a gained about .5 mpg as a result. However, I wouldn't run a decent set of tires above the recommended pressure. It will increase your gas mileage slightly, but may cause the center of the tread to wear quicker than the sides of the tread. Also, it will make the Trib's firm ride even harsher. Most significant is the fact that too much air pressure may change the handling characteristics of a vehicle with a high ground clearance and a short wheelbase...not a safe combination.
#40
05-21-2010, 11:16 AM
I have a 01 tribute v6 3.0 and it has gotton really bad on fuel i get about 270 to 300 km per tank of fuel now my engine light is on with the code p0430 but i couple of years ago i had the catalytic converter cut off because it was pluged up and everything was fine untill a couple of weeks ago my light came on and it is really really bad on fuel does anyone know what i could do to get my milage back to where it should be
please help me
please help me