Reducing rolling resistance?
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Reducing rolling resistance?
Anyway to reduce the rolling resistance?
I had an '06 GTI that was comparable in weight(2850) to my '06
S...but I could pop the dub into neutral and it was soooo free rolling..
have to think this ease would carry over to all around car performance.
My VW had 17" Monte Carlo wheels(I miss them!)..but I dont think they
were that much lighter than my Honda 17" OEM's.
Is it the bigger tire/wheel diameter...would maybe a switch to AP1 wheels help(16")?
maybe if I went with stiffer springs/better dampers than the '06 offers?
thanks!
Joined: Feb 2007
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From: Pawtucket, RI
Reducing toe will reduce rolling resistance significantly. When I went from ~0.5* total rear toe to 0.15*, mileage immediately went up by more than 10%. Went from getting 26-28mpg to getting 29-31mpg.
Wheel weight won't have a big direct impact on rolling resistance. Bigger rotational inertia will take more torque to spin up, but would also act to increase coasting distances. The net effect would be that heavier wheels will increase overall rolling resistance only by the amount that they increase total vehicle weight (i.e., 20 lb less wheel weight => less than one percent reduction in r.r.).
However, *tire* weight does impact rolling resistance. Heavier tires will sap more energy as they are deformed under the weight of the car.
17" vs. 16" also won't have a big impact. In fact, lower-profile tires will *generally* have reduced rolling resistance, but it's not going to be anything you would be able to detect.
Besides alignment, tire inflation pressure is the other big driver. If you want less rolling resistance, pump them up to maybe 34-36psi cold, that would knock it down some.
Wheel weight won't have a big direct impact on rolling resistance. Bigger rotational inertia will take more torque to spin up, but would also act to increase coasting distances. The net effect would be that heavier wheels will increase overall rolling resistance only by the amount that they increase total vehicle weight (i.e., 20 lb less wheel weight => less than one percent reduction in r.r.).
However, *tire* weight does impact rolling resistance. Heavier tires will sap more energy as they are deformed under the weight of the car.
17" vs. 16" also won't have a big impact. In fact, lower-profile tires will *generally* have reduced rolling resistance, but it's not going to be anything you would be able to detect.
Besides alignment, tire inflation pressure is the other big driver. If you want less rolling resistance, pump them up to maybe 34-36psi cold, that would knock it down some.
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What are you trying to do here?
1. Cause it to roll backwards more easily?
2. Improve MPG?
In case #2 your driving could likely be changed before any money was spent to save on gas.
I changed from cheapy tires to star specs a few months ago. Lost 2-3mpg freeway and noted the increased rolling resistance.
1. Cause it to roll backwards more easily?
2. Improve MPG?
In case #2 your driving could likely be changed before any money was spent to save on gas.
I changed from cheapy tires to star specs a few months ago. Lost 2-3mpg freeway and noted the increased rolling resistance.
Joined: Feb 2007
Posts: 6,863
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From: Pawtucket, RI
I don't know if I agree with the notion that "sticky" performance tires necessarily increase rolling resistance. In normal operating conditions it's not like the tire is *adhering* to the tarmac and extra force is having to be used to overcome the "stickiness".
That said, rolling resistance is not near the top priority list for serious performance tires, and there are tires that are emphatically *not* performance tires that are specifically designed to be low rolling resistance.
FWIW, I was on winter tires (Dunlop WinterSport 3d/M3) when I recently had my rear toe-in adjusted down from ~.5* total to .15 total and got a significant mileage benefit (from 26-28 to 29-31). Now I'm back on Star Specs as of a few weeks ago and the mileage has dropped to 28-30 for the first three tankfuls, but that's well within the range of error for my calculating mileage at fillups.
That said, rolling resistance is not near the top priority list for serious performance tires, and there are tires that are emphatically *not* performance tires that are specifically designed to be low rolling resistance.
FWIW, I was on winter tires (Dunlop WinterSport 3d/M3) when I recently had my rear toe-in adjusted down from ~.5* total to .15 total and got a significant mileage benefit (from 26-28 to 29-31). Now I'm back on Star Specs as of a few weeks ago and the mileage has dropped to 28-30 for the first three tankfuls, but that's well within the range of error for my calculating mileage at fillups.
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From: Seabrook, MD
Originally Posted by rob-2,May 16 2010, 12:40 PM
I changed from cheapy tires to star specs a few months ago. Lost 2-3mpg freeway
45PSI, here I come!
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From: Houston, TX
Originally Posted by merckx racer,May 16 2010, 09:59 AM
Anyway to reduce the rolling resistance?
During stop-and-go city driving, it's estimated that overcoming inertia is responsible for about 35% of the vehicle's resistance. Driveline friction is about 45%; air drag is about 5% and tire rolling resistance is about 15%.
Overcoming inertia no longer plays an appreciable role in the vehicle's resistance during steady speed highway driving. For those conditions it is estimated that driveline friction is about 15%; air drag is about 60% and tire rolling resistance represent about 25%.
Overcoming inertia no longer plays an appreciable role in the vehicle's resistance during steady speed highway driving. For those conditions it is estimated that driveline friction is about 15%; air drag is about 60% and tire rolling resistance represent about 25%.
Tire rolling resistance is caused by the natural viscoelastic properties of rubber along with the tire’s internal components constantly bending, stretching and recovering as they cycle between their loaded (where the tread footprint flattens against the road) and unloaded states. The final contributor to tire rolling resistance is the tread’s interaction with the road.
The tread area represents a new tire’s single largest and heaviest region and is the greatest contributor to tire rolling resistance. The tread and its underlying plies typically account for about 2/3 of a new tire’s rolling resistance, while the sidewall and bead area represent the remaining 1/3.
Larger tires require more rubber and longer reinforcing cords than smaller tires. Therefore within a single tire model line, there is typically a relationship between tire size, weight and the resulting rolling resistance force where larger tires have more rolling resistance than smaller tires.
The tread area represents a new tire’s single largest and heaviest region and is the greatest contributor to tire rolling resistance. The tread and its underlying plies typically account for about 2/3 of a new tire’s rolling resistance, while the sidewall and bead area represent the remaining 1/3.
Larger tires require more rubber and longer reinforcing cords than smaller tires. Therefore within a single tire model line, there is typically a relationship between tire size, weight and the resulting rolling resistance force where larger tires have more rolling resistance than smaller tires.
