LOW ROLLING RESITANCE TIRES

1
LOW ROLLING RESITANCE TIRES

• A presentation by Jason GreenblattM.S. in
  Mechanical Engineering
• of San Diego Gas Electric

2
GENERAL DEFINITION

• Low rolling resistance tires are tires which
  are designed to improve fuel efficiency of a car
  (particularly hybrids) by minimizing the energy
  wasted as heat as the tire rolls down the road.
• GENERAL DEFINTION
• THREAD DESIGN AND PATTERNS
• CHOICE OF TIRE
• TIRE PRESSURE
• SAVING GAS
• ENVIRONMENTAL FACTS
• CONCLUSION

3
GENERAL INFORMATION
4
GENERAL DEFINITION

• Gas mileage is affected by more than just
• the size and weight of the tire. Rolling
• resistance of the tire has a larger effect.
• Here's the basic rule
• Harder tires lower rolling resistance

5
GENERAL DEFINITION

• Most of the hybrid vehicles use some sort of
  low rolling resistance tire. Sometimes these
  tires are called low m. m (or mu) is used as the
  symbol for tire friction to the road surface.

6
CAUTION

• If the tire is too hard or too round, then
  the tire-patch (which is the area of tire that is
  in contact with the ground) will be too small to
  grip the road surface effectively. This in turn
  will allow the wheel to skid easier when trying
  to stop or allow the wheel to slip and spin when
  trying to roll out from a light.

7
TREAD DESIGNS AND PATTERNS

• The more detailed the tread design, the more
  likely it will grip the road better
• But this also creates the opportunity to trap
  air in each of the pockets it generates when
  touching the road surface.

8
TREAD DESIGNS AND PATTERNS

• When trapping the air/water/dirt/snow in
  these pockets, the tire is compressing the
  material that is in the pocket.
• Therefore, the engine has to do more work to
  compress these pockets. This makes the tire less
  efficient to turn, and thereby reduces the
  mileage of the vehicle.

9
TREAD DESIGNS AND PATTERNS

• It boils down to personal preference. If you
  drive aggressively, you might want to use a
  softer tire with better road adhesion. If youre
  a fanatic for mileage and a very mellow driver,
  then you probably should get the lowest
  resistance tire you can find on the market.

10
CHOICE OF TIRE

• You can minimize resistance, and maximize mpg
  or range by using Low Rolling Resistance (LRR)
  rated tires.
• If you change your vehicles tires, by
  increasing or decreasing the resistance by 20,
  for example, you may raise or drop mileage by 3
  to 5.

11
CHOICE OF TIRE and TIRE PRESSURE

• While this is a measurable difference, it
  wont make as big a difference as making certain
  that your tires are properly inflated.

12
(No Transcript)
13
KEY INFORMATION FOUND ON TIRES
14
(No Transcript)
15
TIRE PRESSURE

• Many hybrid car enthusiasts recommend
  anabsolute minimum of 35 psiand many try to
  push the envelope by increasing pressure to 40
  psi. Prius advises 40 psi rear, 42 psifront for
  1st Generation (2001-2004) models.
• Read the manufacturers recommendations
  there could be safety issues related to
  over-inflating your tires.

16
TIRE PRESSURE

• Remember that temperature makes a
  difference.The rule of thumb is for every 10
  Fahrenheit change in air temperature, your
  tire's inflation pressure will change by about 1
  psi (up with higher temperatures and down with
  lower). When it gets cold, check your pressure to
  make sure it's not too low.

17
SAVING FUEL

• According to research for the California
  Energy Commission, about 1.5 to 4.5 of total
  gasoline used could be saved if all replacement
  tires in use had low rolling resistance. This
  translates roughly into average savings of up to
  30 gallons of gasoline savings per vehicle per
  year, or from 2.5 to 7.5 billion worth of
  national average gasoline savings.

18
ENVIORNMENTAL FACTS
With over 160 million passenger cars and light
trucks on the road, we burn about 126 billion
gallons of gasoline per year. Our fuel use
continues to rise, about 3 annually, propelled
by continued increases in total number of
vehicles, rising average distance driven per car,
and falling average fuel economy.
19
A monster motor home that was towing the
SUV of all SUV's, a golden hued Hummer
20
ENVIRONMENTAL FACTS
Today, light-duty vehicles (cars light trucks)
are responsible for about 20 of the nitrogen
oxides, 27 of the volatile organic compounds,
51 of the carbon monoxide, and roughly 30 of
all the carbon dioxide (the main greenhouse gas)
emitted from human activities nationwide.
21
CONCLUSION
One of the most promising opportunities for fuel
savings across all existing vehicles is to
utilize low rolling resistance tires instead of
standard replacement models. The change improves
the inherent efficiency of the vehicle,
automatically saving fuel over the typical 30,000
to 50,000 mile lifetime of a set of tires.
22
ENVIRONMENTAL FACTS

• Increasing fuel use also has enormous
  implications for protection of wilderness and
  public lands (vulnerable to increased
  exploration), water resources (vulnerable to
  tanker and pipeline accidents), and national
  security.

23
(No Transcript)
24
LOW ROLLING RESITANCE TIRESJason Greenblatt,
M.S. San Diego Gas Electric