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Why I chose 245/70R17 tires over 265/65/17
I chose Hercules terra trac II. 30.49, 9.79" wide, 38.4lbs each
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I know wider looks better and I am a huge fan of this look but I wanted function so 245/70R17 makes more sense while also giving me a .5" lift. I think wider serves a purpose but not for street to off-road use. I don't plan on much sand and if I do, I will lower tire pressures to have a wider patch.
Why is taller better than wider?
1) Taller tires have a longer footprint that is in line with the pull of the wheel. 2) The part of a tire that normally loses grip is smaller on a tall tire. 3) A contact point on a tall tire is in touch with the ground for a longer time than a wide tire. 4) Taller tires have a longer patch to conform to the structure of the ground therefore has better grip. 5) Taller tires are less abusive on wheel bearings. 6) Torque to the ground decrease with increased tire height. 7) Taller tires have less effect on the environment since they are less likely to spin or slip.
For a given surface area and aspect ratio a taller tire is better than a wider tire for a majority of technical off road driving
"Less rotating mass- Easier to start and stop
Less reciprocating mass- Easier to dampen
Less wind resistance- Better economy and range
Less rolling resistance- Better economy and range
Easier to fit a taller/narrower tire with less lift
Lighter spare
Lighter tire
Lighter wheel
Less unsprung weight
Less weight and leverage on steering components, bearings, etc.
In terrain:
1. Less frontal resistance in mud and sand. Where is most of the increased contact patch (for flotation) gained? In the length, not the width. Tall and narrow allows for more length and greater deformation with less resistance.
It is as simple as understanding the coefficient of friction (COF), which is (Ff = Cf x Fv).
Ff= Friction Force
Cf= Coefficient of Friction
Fv= Force Vertical
As you make a tire wider, you reduce the Fv over a larger area, but gain Cf. As you make a tire narrower, you increase the Fv, but reduce the area of contact, which lowers the Cf. It is proportional, though there are times when the material interaction (lets say a drag tire on concrete) favors Cf, but those conditions rarely exist on the trail, on a perfectly flat surface. So, if a wide and narrow tires benefits with relationship to Cf and Fv are proportional, than the decision must be made on other factors, like weight, resistance, etc., as listed above.
Now of course, there are limits at both ends of the spectrum. Too narrow of a tire, and the torque applied to the surface, even with extremely high Fv (which a super narrow tire would have), would exceed the rubbers ability to resist tearing. Literally, burning rubber.
Big, fat tires are only for show trucks and tundra buggies. An expedition vehicle has an emphasis on simplicity, economy, durability and safety
also this: http://www.overlandexperts.com/docs/articles/offroad_tire_taller_or_wider.pdf
I chose Hercules terra trac II. 30.49, 9.79" wide, 38.4lbs each
I know wider looks better and I am a huge fan of this look but I wanted function so 245/70R17 makes more sense while also giving me a .5" lift. I think wider serves a purpose but not for street to off-road use. I don't plan on much sand and if I do, I will lower tire pressures to have a wider patch.
Why is taller better than wider?
1) Taller tires have a longer footprint that is in line with the pull of the wheel. 2) The part of a tire that normally loses grip is smaller on a tall tire. 3) A contact point on a tall tire is in touch with the ground for a longer time than a wide tire. 4) Taller tires have a longer patch to conform to the structure of the ground therefore has better grip. 5) Taller tires are less abusive on wheel bearings. 6) Torque to the ground decrease with increased tire height. 7) Taller tires have less effect on the environment since they are less likely to spin or slip.
For a given surface area and aspect ratio a taller tire is better than a wider tire for a majority of technical off road driving
"Less rotating mass- Easier to start and stop
Less reciprocating mass- Easier to dampen
Less wind resistance- Better economy and range
Less rolling resistance- Better economy and range
Easier to fit a taller/narrower tire with less lift
Lighter spare
Lighter tire
Lighter wheel
Less unsprung weight
Less weight and leverage on steering components, bearings, etc.
In terrain:
1. Less frontal resistance in mud and sand. Where is most of the increased contact patch (for flotation) gained? In the length, not the width. Tall and narrow allows for more length and greater deformation with less resistance.
It is as simple as understanding the coefficient of friction (COF), which is (Ff = Cf x Fv).
Ff= Friction Force
Cf= Coefficient of Friction
Fv= Force Vertical
As you make a tire wider, you reduce the Fv over a larger area, but gain Cf. As you make a tire narrower, you increase the Fv, but reduce the area of contact, which lowers the Cf. It is proportional, though there are times when the material interaction (lets say a drag tire on concrete) favors Cf, but those conditions rarely exist on the trail, on a perfectly flat surface. So, if a wide and narrow tires benefits with relationship to Cf and Fv are proportional, than the decision must be made on other factors, like weight, resistance, etc., as listed above.
Now of course, there are limits at both ends of the spectrum. Too narrow of a tire, and the torque applied to the surface, even with extremely high Fv (which a super narrow tire would have), would exceed the rubbers ability to resist tearing. Literally, burning rubber.
Big, fat tires are only for show trucks and tundra buggies. An expedition vehicle has an emphasis on simplicity, economy, durability and safety
also this: http://www.overlandexperts.com/docs/articles/offroad_tire_taller_or_wider.pdf
