Gas Mileage Test: Tire Weight
12-23-2012, 02:24 PM
#11
Senior Member
Join Date: 11-29-2007
Location: Wilmington,Illinois
Posts: 175
I keep records in a spred sheet and this was one sub set of the spread sheet on mpg vs tires. A complete mix of seasons, long trips, short trips and various gasoline brands. At one std dev, the mpg overlap. I'm still trying to figure out why the Cooper Tires dropped the mpg average by 2-3 mpg.
One of these days I may break down mpg by gasoline brands.
The HHR has ~104,000 miles on the clock.
..fillups.....mpg................................s td dev
n=161.... 30.52... original tires....... 2.937203692
n=109.... 31.0.... Good years tires.. 2.859761562
n=35..... 28.2.... Cooper tires...... 2.126855393
One of these days I may break down mpg by gasoline brands.
The HHR has ~104,000 miles on the clock.
..fillups.....mpg................................s td dev
n=161.... 30.52... original tires....... 2.937203692
n=109.... 31.0.... Good years tires.. 2.859761562
n=35..... 28.2.... Cooper tires...... 2.126855393
12-30-2012, 08:37 AM
#12
Banned
Join Date: 07-12-2010
Location: florida
Posts: 74
I like your attention to detail. Never really thought about tire weight loss as it wears. One good thing about a heavier tire is the fly wheel effect, which once up to speed is a plus. Mostly highway miles it should increase mpg. decrease in the city stop and go traffic.
What brand or design of tire has proven to get the best mileage?
What brand or design of tire has proven to get the best mileage?
01-01-2013, 10:46 AM
#13
Senior Member
Join Date: 01-14-2011
Location: north ga
Posts: 175
here is my small amount of information
set 1 Firestone OEM 17 " on Forged aluminum Wheel lasted 70,000 miles mpg 29.6
set 2 Yokohoma YK 520 On same wheels lasted 75,000 miles mpg 30.2
set 3 Nexen N 5000 on same wheels lasted 40,000 miles mpg 28.6
set 4 Falken Ziex ZE-612 same wheel have 13,566 miles on them mpg 28.2
the last two sets handled the best and the Falkens are by far the noisiest. I have always used mobil 1. live in the south. only use shell premium gas. And use lucas every time i change the oil to clean fuel injectors. Used the same process on my 1996 Ford explorer which has 450,000 miles with no one going into motor or transmission. Seems to me that the softer better handling tires cause me some mpg. What are ya'll esteemed thoughts.
set 1 Firestone OEM 17 " on Forged aluminum Wheel lasted 70,000 miles mpg 29.6
set 2 Yokohoma YK 520 On same wheels lasted 75,000 miles mpg 30.2
set 3 Nexen N 5000 on same wheels lasted 40,000 miles mpg 28.6
set 4 Falken Ziex ZE-612 same wheel have 13,566 miles on them mpg 28.2
the last two sets handled the best and the Falkens are by far the noisiest. I have always used mobil 1. live in the south. only use shell premium gas. And use lucas every time i change the oil to clean fuel injectors. Used the same process on my 1996 Ford explorer which has 450,000 miles with no one going into motor or transmission. Seems to me that the softer better handling tires cause me some mpg. What are ya'll esteemed thoughts.
01-01-2013, 02:50 PM
#14
Senior Member
Join Date: 01-13-2008
Location: Washington State, where it rains
Posts: 4,708
My guess..with the softer tires...you would have increased rolling resistance due to the tire patch balling up in front and the fwd momentum having to overcome this, this may be old school thinking from back when radials first came out. A harder tire would have a lesser tendency to do this making the tire easier to roll..also a wider tire increases rolling resistance as more tire is in contact with the road. This is why the experimental machines ( solar..petal..electric ) all use the skinniest tires possible, to decrease frontal area and rolling resistance..
01-25-2013, 12:53 PM
#15
Thread Starter
Join Date: 05-15-2010
Location: Nashville TN
Posts: 4
Here is some good information from a reputable source!
Source:
Tire Review - Online
1/25/2013
Link: http://www.tirereview.com/Article/10...ing_prove.aspx
"Rolling Resistance Factors
Rolling resistance is the force required to move a loaded tire at a constant speed, on a level road in a straight line; it primarily is caused by the high hysteresis of rubber compounds.
Hysteresis is the characteristic of any material that causes the energy requir¬ed to deform the material to be greater than the energy of its recovery. Rubber's high hysteresis means it bounces back slowly and with more resistance than a material like steel that bounces back faster and more completely.
The combination of hysteresis, the tread's interaction with the road surface, and cycling of the tire's internal components as the tire rotates through repeated cycles of deformation and recovery produces rolling resistance.
The tread and its underlying plies are a tire's heaviest and largest components and create most of its rolling resistance – typically about two-thirds of the total. The sidewall and bead area account for the remaining one-third. Because larger tires contain more rubber and internal components than smaller tires, within one particular tire model line, larger sizes will have more rolling resistance than smaller sizes.
There are two principal standards for measuring rolling resistance: rolling resistance force and the rolling resistance coefficient. Rolling resistance force measures energy loss per unit of distance in pounds of resistance. By comparing rolling resistance force, tires of the same or different sizes can be readily and accurately compared.
The tire rolling resistance coefficient is calculated by dividing the measured rolling resistance force of a particular size tire by its load rating. Rolling resistance varies with the load on a tire, so tires with different load indexes are tested at different loads.
With rolling resistance coefficient, larger tires may have a lower rolling resistance coefficient than smaller tires, even though larger tires generally have higher rolling resistance forces. Consequently, rolling resistance coefficients only allow realistic comparisons among tires within a single size.
The NHTSA test will be based on calculated rolling resistance force using the ISO 28580 Draft International Standard the EU selected for its rolling resistance rating system. This should allow harmonization of the U.S. and European standards and test practices.
RR and Fuel Economy
Fuel economy is determined by a vehicle's total resistance to movement, including aerodynamic drag, driveline friction, inertia, the grade of the roadway and tire rolling resistance. Typically, tire rolling resistance is only 15% of a vehicle's total resistance in stop-and-go driving. Driveline friction is the largest component at 45%, overcoming inertia represents 35% and aerodynamic drag 5%.
Once out on the highway in relatively steady speed conditions, tire rolling resistance generally represents about 25% of total rolling resistance while aerodynamic drag rises dramatically to about 60%. Driveline friction is only about 15% of the total and overcoming inertia is not a significant factor.
The impact of tire rolling resistance on fuel economy ranges from 4% in city driving to 7% on the highway. Auto manufacturers typically estimate that a 10% reduction in tire rolling resistance will result in a 1% to 2% improvement in vehicle fuel economy. NHTSA found that a 10% decrease in tire rolling resistance resulted in a 1.1% increase in fuel economy.
Vehicle manufacturers have continued to demand low rolling resistance tires as OE to help achieve CAFE standards. Tiremakers have responded with reduced weight tires molded with thinner sidewalls, shallower tread depths, and low rolling resistance tread with silica replacing carbon black.
Does It Really Matter?
How much of an actual difference is a set of these lower rolling resistance tires going to make to the consumer? Consider a situation where low rolling resistance replacement tires have a huge 20% decrease in rolling resistance vs. the existing tires.
We need to multiply the portion of the tires' influence on overall rolling resistance (15% city and 25% highway) by the 20% decrease in tire rolling resistance to calculate the potential change in miles per gallon.
If the vehicle previously provided 25 mpg in the city and 30 mpg on the highway, the calculated increase in fuel mileage for tires with 20% lower rolling resistance would be 3% (25.75 mpg) in city driving and 5% (31.5 mpg) on the highway. A measurable difference, but there are some hurdles to achieving the calculated savings.
First, the new tires may not initially provide lower rolling resistance as full-tread tires generate more rolling resistance than worn tires. Because of the reduction in tread mass and hardening of the tread compound, tire rolling resistance usually drops 20% during a tire's life. While the gradual reduction in rolling resistance and any subtle increase in fuel mileage probably went unnoticed, the installation of new tires (even with 20% lower rolling resistance) is likely to be a break-even and may even cause a decrease in fuel mileage.
Also, new, full-tread passenger car tires are typically 0.5-inch larger in diameter than identical worn-out tires. So the revolutions per mile for the new tire may cause the vehicle's odometer to understate the actual miles driven by 1% to 2%, and fuel economy would appear to decline a like amount.
Finally, tires branded as the same size may vary in their specifications by manufacturer and model. Passenger car tires sometimes vary by as much as 0.2-inch in diameter, with resulting differences in revolutions per mile. If a tire rolls fewer times per mile than the tire it replaces, the vehicle will actually be traveling farther than indicated by the odometer.
Individually, these factors are probably not significant. However, when added together, a consumer's new low rolling resistance tires may not produce the expected improvement in fuel economy. If OE low rolling resistance tires were replaced, the new tires may even appear to reduce fuel mileage.
On the other hand, correct tire pressure may be as important as the tires themselves. A 20% reduction in inflation pressure (from 35 psi to 28 psi) may increase tire rolling resistance 10% or more resulting in a 1% to 2% reduction in fuel economy.
The key seems to be in understanding the numbers. Reductions in tire rolling resistance only reduce a portion of the vehicle's total rolling resistance.
Valid comparisons between tires can only be made within a particular tire classification (e.g. standard touring vs. standard touring), and while lower rolling resistance tires can enhance fuel economy, the day-to-day difference is not large. "
Source:
Tire Review - Online
1/25/2013
Link: http://www.tirereview.com/Article/10...ing_prove.aspx
"Rolling Resistance Factors
Rolling resistance is the force required to move a loaded tire at a constant speed, on a level road in a straight line; it primarily is caused by the high hysteresis of rubber compounds.
Hysteresis is the characteristic of any material that causes the energy requir¬ed to deform the material to be greater than the energy of its recovery. Rubber's high hysteresis means it bounces back slowly and with more resistance than a material like steel that bounces back faster and more completely.
The combination of hysteresis, the tread's interaction with the road surface, and cycling of the tire's internal components as the tire rotates through repeated cycles of deformation and recovery produces rolling resistance.
The tread and its underlying plies are a tire's heaviest and largest components and create most of its rolling resistance – typically about two-thirds of the total. The sidewall and bead area account for the remaining one-third. Because larger tires contain more rubber and internal components than smaller tires, within one particular tire model line, larger sizes will have more rolling resistance than smaller sizes.
There are two principal standards for measuring rolling resistance: rolling resistance force and the rolling resistance coefficient. Rolling resistance force measures energy loss per unit of distance in pounds of resistance. By comparing rolling resistance force, tires of the same or different sizes can be readily and accurately compared.
The tire rolling resistance coefficient is calculated by dividing the measured rolling resistance force of a particular size tire by its load rating. Rolling resistance varies with the load on a tire, so tires with different load indexes are tested at different loads.
With rolling resistance coefficient, larger tires may have a lower rolling resistance coefficient than smaller tires, even though larger tires generally have higher rolling resistance forces. Consequently, rolling resistance coefficients only allow realistic comparisons among tires within a single size.
The NHTSA test will be based on calculated rolling resistance force using the ISO 28580 Draft International Standard the EU selected for its rolling resistance rating system. This should allow harmonization of the U.S. and European standards and test practices.
RR and Fuel Economy
Fuel economy is determined by a vehicle's total resistance to movement, including aerodynamic drag, driveline friction, inertia, the grade of the roadway and tire rolling resistance. Typically, tire rolling resistance is only 15% of a vehicle's total resistance in stop-and-go driving. Driveline friction is the largest component at 45%, overcoming inertia represents 35% and aerodynamic drag 5%.
Once out on the highway in relatively steady speed conditions, tire rolling resistance generally represents about 25% of total rolling resistance while aerodynamic drag rises dramatically to about 60%. Driveline friction is only about 15% of the total and overcoming inertia is not a significant factor.
The impact of tire rolling resistance on fuel economy ranges from 4% in city driving to 7% on the highway. Auto manufacturers typically estimate that a 10% reduction in tire rolling resistance will result in a 1% to 2% improvement in vehicle fuel economy. NHTSA found that a 10% decrease in tire rolling resistance resulted in a 1.1% increase in fuel economy.
Vehicle manufacturers have continued to demand low rolling resistance tires as OE to help achieve CAFE standards. Tiremakers have responded with reduced weight tires molded with thinner sidewalls, shallower tread depths, and low rolling resistance tread with silica replacing carbon black.
Does It Really Matter?
How much of an actual difference is a set of these lower rolling resistance tires going to make to the consumer? Consider a situation where low rolling resistance replacement tires have a huge 20% decrease in rolling resistance vs. the existing tires.
We need to multiply the portion of the tires' influence on overall rolling resistance (15% city and 25% highway) by the 20% decrease in tire rolling resistance to calculate the potential change in miles per gallon.
If the vehicle previously provided 25 mpg in the city and 30 mpg on the highway, the calculated increase in fuel mileage for tires with 20% lower rolling resistance would be 3% (25.75 mpg) in city driving and 5% (31.5 mpg) on the highway. A measurable difference, but there are some hurdles to achieving the calculated savings.
First, the new tires may not initially provide lower rolling resistance as full-tread tires generate more rolling resistance than worn tires. Because of the reduction in tread mass and hardening of the tread compound, tire rolling resistance usually drops 20% during a tire's life. While the gradual reduction in rolling resistance and any subtle increase in fuel mileage probably went unnoticed, the installation of new tires (even with 20% lower rolling resistance) is likely to be a break-even and may even cause a decrease in fuel mileage.
Also, new, full-tread passenger car tires are typically 0.5-inch larger in diameter than identical worn-out tires. So the revolutions per mile for the new tire may cause the vehicle's odometer to understate the actual miles driven by 1% to 2%, and fuel economy would appear to decline a like amount.
Finally, tires branded as the same size may vary in their specifications by manufacturer and model. Passenger car tires sometimes vary by as much as 0.2-inch in diameter, with resulting differences in revolutions per mile. If a tire rolls fewer times per mile than the tire it replaces, the vehicle will actually be traveling farther than indicated by the odometer.
Individually, these factors are probably not significant. However, when added together, a consumer's new low rolling resistance tires may not produce the expected improvement in fuel economy. If OE low rolling resistance tires were replaced, the new tires may even appear to reduce fuel mileage.
On the other hand, correct tire pressure may be as important as the tires themselves. A 20% reduction in inflation pressure (from 35 psi to 28 psi) may increase tire rolling resistance 10% or more resulting in a 1% to 2% reduction in fuel economy.
The key seems to be in understanding the numbers. Reductions in tire rolling resistance only reduce a portion of the vehicle's total rolling resistance.
Valid comparisons between tires can only be made within a particular tire classification (e.g. standard touring vs. standard touring), and while lower rolling resistance tires can enhance fuel economy, the day-to-day difference is not large. "
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