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Thread: Bigger Tire Size is BAD and more dangerous.

  1. #21
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    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Silence Sky View Post
    I think... when the aspect ratio decreases for a wider tire, the side wall height is still about the same.

    175 * 65% = 113.75
    205 * 55% = 112.75

    But I can confirm 16" is definitely heavier than 15" tire, because more expansive meh.

    Wah you are a speed monster leh.
    Going at 250km/h on your motorbike!!!! Some more in wet condition
    You are crazy...
    Yeah 16" is defintely heavier than 15". In that case, the primarily factor here should be replacing a light weight racing rims that downsizing the width of the tires. Then again, how many people are willing to spend S$4k alone on rims (exclude tires).

    Its quite achievable on the straights in Sepang, plus the road surface is unlike our normal roads.

  2. #22
    Senior Member Big Kahuna's Avatar
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    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Silence Sky View Post
    Hi,, we are debating on the wider tire does not hold the road better than a smaller tire, leh.
    Better control, I think yes..

    I don't understand why require high output engine for better traction.
    You are dangerous man...u took my word out of context....I said "wider tyre is require for high output engine for better traction".....you omitted the red part....they are totally not the same in meaning

    Anyhow...wiki may have some clue for you if you are good in figures

    http://en.wikipedia.org/wiki/Tractio...ion_trade-offs
    Last edited by Big Kahuna; 16th June 2008 at 11:59 PM.

  3. #23

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Big Kahuna View Post
    You are dangerous man...u took my word out of context....I said "wider tyre is require for high output engine for better traction".....you omitted the red part....they are totally not the same in meaning

    Anyhow...wiki may have some clue for you if you are good in figures

    http://en.wikipedia.org/wiki/Tractio...ion_trade-offs
    Sorry Brother...
    If add in the red color words, i lagi catch no ball. Maybe you can explain in other words to help me understand better. Do you mean, given a high torque engine, a wider tire can provide more traction than a small tire?

    I am trying to digest the information in the link you have provided, too profound for me.

  4. #24

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Lmodel View Post
    Yeah 16" is defintely heavier than 15". In that case, the primarily factor here should be replacing a light weight racing rims that downsizing the width of the tires. Then again, how many people are willing to spend S$4k alone on rims (exclude tires).

    Its quite achievable on the straights in Sepang, plus the road surface is unlike our normal roads.
    that again, if the wheels are ligther now, the traction between the road and tire will also decrease, isn't it?

  5. #25
    Senior Member Big Kahuna's Avatar
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    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Silence Sky View Post
    Sorry Brother...
    If add in the red color words, i lagi catch no ball. Maybe you can explain in other words to help me understand better. Do you mean, given a high torque engine, a wider tire can provide more traction than a small tire?

    I am trying to digest the information in the link you have provided, too profound for me.
    Wider tire is one of the factor to improve the traction.....chances of seeing white smokes when open up the throttle will increase

  6. #26

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Big Kahuna View Post
    You are dangerous man...u took my word out of context....I said "wider tyre is require for high output engine for better traction".....you omitted the red part....they are totally not the same in meaning

    Anyhow...wiki may have some clue for you if you are good in figures

    http://en.wikipedia.org/wiki/Tractio...ion_trade-offs
    Hi, I roughly read through the page. I can undestand most of the points, but it did not mention High torque engine with wider tire = more traction.

    "Traction between two surfaces usually depends on several factors including

    Material properties of each surface.
    Macroscopic and microscopic shape or "roughness".
    Force of contact.
    Area of contact.
    Contaminants at the material boundary including lubricants and adhesives.
    "

    To prove my points, here's what is says in the page:
    "bicycle tires have a narrow and pointed area of contact, so even slick tires give good traction on a wet pavement."

    Maybe that's is why Lmodel can travel 250km/h on his bike on wet surface.
    His trie is cone shape can better channel water away from the tire.

  7. #27

    Default Re: Bigger Tire Size is BAD and more dangerous.

    this discussion can drag & drift........but here's my contribution ;

    ferraris, lambos, maseratis, pagani zondas, bugatti veyron, porsches.....

    these performance cars NEED bigger & wider tyres & rims set-up n they come Standard specs, low profile naturally. Y? becos their engines are meant to sprint & hence the need for better grip, handling.

    these manufacturers spend Millions of dollars doing research & applying the appropriate sizes for their almost million dollar a piece machines they preciously invented since day 1.

    the topic refers appropriate only for small to mid sized saloon cars, which their respective manufacturers have done equally amount of research work to blend the physics in.

    now here's the clear picture.

    there is no standard tyre/rim set up size for all cars.

    each car size, capacity & performance need different appropriate specs.

    imagine driving a ferrari with 195/55/15 set up.

    they will go bust !!

    (it's not how fast you can go from 0-150km/h ..but how fast can you brake & stop from 150km/h-0km/h )

  8. #28

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Big Kahuna View Post
    Wider tire is one of the factor to improve the traction.....chances of seeing white smokes when open up the throttle will increase
    Ok, I hear you.
    We are trying to prove that wider/bigger tire (given the same load and tire pressure) will not increase the traction.

  9. #29
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    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Silence Sky View Post

    To prove my points, here's what is says in the page:
    "bicycle tires have a narrow and pointed area of contact, so even slick tires give good traction on a wet pavement."

    Ok. Now I do a hell of a lot of cycling and I can tell you that the type of tyre is linked to the terrain. Any manner of loose surface and slick tires are completely useless. Furthermore, if thin tires have so much more grip why do motorbikes (not to mention F1 cars) have so much more rubber on the road? Why don't they just whiz around on super thin tires?

    Aquaplaning aside, there is some correlation between the ammount of rubber you put on the road and how much grip you have. The reason you use more fuel with thicker tires is because more traction also equals more resistance, that is how tires work. Nothing comes for free. Certainly, an F1 car would ultimately be able to go much faster (top speed) with tiny thin tires, but the lack of traction would mean that the ammount of torque placed on the wheels would far exceed the abilty of them to grip the road surface, causing them to spin out.
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  10. #30

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by D60D60 View Post
    this discussion can drag & drift........but here's my contribution ;

    ferraris, lambos, maseratis, pagani zondas, bugatti veyron, porsches.....

    these performance cars NEED bigger & wider tyres & rims set-up n they come Standard specs, low profile naturally. Y? becos their engines are meant to sprint & hence the need for better grip, handling.

    these manufacturers spend Millions of dollars doing research & applying the appropriate sizes for their almost million dollar a piece machines they preciously invented since day 1.

    the topic refers appropriate only for small to mid sized saloon cars, which their respective manufacturers have done equally amount of research work to blend the physics in.

    now here's the clear picture.

    there is no standard tyre/rim set up size for all cars.

    each car size, capacity & performance need different appropriate specs.

    imagine driving a ferrari with 195/55/15 set up.

    they will go bust !!

    (it's not how fast you can go from 0-150km/h ..but how fast can you brake & stop from 150km/h-0km/h )

    No doubt, you have valid points.

    However, the problem statement is: "wider tire = more Traction (Given that load and Air pressure remain constant).

    In your Farrari case: Does a 230 18" gives better traction than a 220 17"?

  11. #31

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Churchwolf View Post
    Ok. Now I do a hell of a lot of cycling and I can tell you that the type of tyre is linked to the terrain. Any manner of loose surface and slick tires are completely useless. Furthermore, if thin tires have so much more grip why do motorbikes (not to mention F1 cars) have so much more rubber on the road? Why don't they just whiz around on super thin tires?

    Aquaplaning aside, there is some correlation between the ammount of rubber you put on the road and how much grip you have. The reason you use more fuel with thicker tires is because more traction also equals more resistance, that is how tires work. Nothing comes for free. Certainly, an F1 car would ultimately be able to go much faster (top speed) with tiny thin tires, but the lack of traction would mean that the ammount of torque placed on the wheels would far exceed the abilty of them to grip the road surface, causing them to spin out.
    I will try to answer your question on why need wider tire.

    Wider tire is needed for better road control, withstand the load of the vehicle and resist rolling during hard conering.

    And on the spin out, I will need to read up more.

  12. #32

    Default Re: Bigger Tire Size is BAD and more dangerous.

    I try to keep the problem statement clear and simplify my thinking by using the schematic diagram below.

    Let say both Block A and Block B is of the same size / weigth / same material / same surface roughness (same RA).

    Now the Question is: Force A or Force B is greater if I want to move the two blocks acrosss the same surface plane?

    Last edited by Silence Sky; 17th June 2008 at 07:07 PM.

  13. #33
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    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Silence Sky View Post
    I try to keep the problem statement clear and simplify my thinking by using the schematic diagram below.

    Let say both Block A and Block B is of the same size / weigth / same material / same surface roughness (same RA).

    Now the Question is: Force A or Force B is greater if I want to move the two blocks acrosss the same surface plane?

    It is a good explanation, but consider this:

    Given a perfect environment (where friction plays no role) moving "Block A" will require the same ammount of energy to overcome inertia as moving "Block B". However friction plays a major role in tire function so this is obviously not the case. Assuming both blocks are made of identical materials (with the grain and orientation of the material being equal on all faces, regardless of orientation), and assuming that the friction/area is uniform "Block A" will require a greater input of force to move than "Block B" because one needs to overcome both inertia and total contact friction.

    I feel that perhaps this discussion is becoming mislead by the belief that a wider tires automatically = greater contact area. Due to a tire's structure it is infact the tire pressure that determines the size of the contact area (which in turn provides friction, which in turn provides the grip exhibited by the tire). The main advantage of using wider tires is that you do not need as much air pressure to ensure that the tire maintains its shape (due to the spreading of load across a larger surface area). This reduced pressure allows you to provide a greater contact patch to the road surface and also reduces the rate at which the tire heats up (because lower pressure = less air molecules = less molecular friction = less heat).

    The problem with wide tires comes when the road surface gets wet. Because water is a liquid and liquids, like solids, cannot be compressed, the width of the tire may trap water under the larger contact patch thereby preventing its contact with the road surface. This is what makes aquaplaning so dangerous, since the tire is effectively trying to "grip" the water and finds virtually no friction thereby robbing the driver of control. Wider tires are at far greater risk of this phenomenon because of the larger contact area they have with the road, and is the main reason that there is such a large difference between "wet" tires and "dry slicks" in racing. Wet tires allow water to be channelled away from the contact patch and allow the remaining rubber to grip the surface of the road safely. However, using wet tires (with their channels) on a dry road provides less grip than a slick tire because some of the rubber surface area is absent due to the channels.

    Essentially, the upshot of this whole discussion will end up being that there is no such thing as the perfect tire. Tire performance, usefulness and safety is determined by a large number of influencing factors including the road surface, the weather, the vehicles geometry and suspension as well as the tire compound and the contained pressure.

    A pretty complicated topic, I think we can all agree!
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  14. #34

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Hi:

    I think we are moving closer in term of thinking...
    That is: Bigger Tire does not equal greater traction but definitely more susceptible to hydroplaning

    But there are still points in your statement I like to challenge.



    Quote Originally Posted by Churchwolf View Post
    It is a good explanation, but consider this:

    Given a perfect environment (where friction plays no role) moving "Block A" will require the same ammount of energy to overcome inertia as moving "Block B". However friction plays a major role in tire function so this is obviously not the case. Assuming both blocks are made of identical materials (with the grain and orientation of the material being equal on all faces, regardless of orientation), and assuming that the friction/area is uniform "Block A" will require a greater input of force to move than "Block B" because one needs to overcome both inertia and total contact friction.

    I feel that perhaps this discussion is becoming mislead by the belief that a wider tires automatically = greater contact area. Due to a tire's structure it is infact the tire pressure that determines the size of the contact area (which in turn provides friction, which in turn provides the grip exhibited by the tire). The main advantage of using wider tires is that you do not need as much air pressure to ensure that the tire maintains its shape (due to the spreading of load across a larger surface area). This reduced pressure allows you to provide a greater contact patch to the road surface and also reduces the rate at which the tire heats up (because lower pressure = less air molecules = less molecular friction = less heat).

    The problem with wide tires comes when the road surface gets wet. Because water is a liquid and liquids, like solids, cannot be compressed, the width of the tire may trap water under the larger contact patch thereby preventing its contact with the road surface. This is what makes aquaplaning so dangerous, since the tire is effectively trying to "grip" the water and finds virtually no friction thereby robbing the driver of control. Wider tires are at far greater risk of this phenomenon because of the larger contact area they have with the road, and is the main reason that there is such a large difference between "wet" tires and "dry slicks" in racing. Wet tires allow water to be channelled away from the contact patch and allow the remaining rubber to grip the surface of the road safely. However, using wet tires (with their channels) on a dry road provides less grip than a slick tire because some of the rubber surface area is absent due to the channels.

    Essentially, the upshot of this whole discussion will end up being that there is no such thing as the perfect tire. Tire performance, usefulness and safety is determined by a large number of influencing factors including the road surface, the weather, the vehicles geometry and suspension as well as the tire compound and the contained pressure.

    A pretty complicated topic, I think we can all agree!

  15. #35

    Default Re: Bigger Tire Size is BAD and more dangerous.

    Quote Originally Posted by Churchwolf View Post

    Given a perfect environment (where friction plays no role) moving "Block A" will require the same ammount of energy to overcome inertia as moving "Block B". However friction plays a major role in tire function so this is obviously not the case. Assuming both blocks are made of identical materials (with the grain and orientation of the material being equal on all faces, regardless of orientation), and assuming that the friction/area is uniform "Block A" will require a greater input of force to move than "Block B" because one needs to overcome both inertia and total contact friction.



    Wider tires are at far greater risk of this phenomenon because of the larger contact area they have with the road, and is the main reason that there is such a large difference between "wet" tires and "dry slicks" in racing. Wet tires allow water to be channelled away from the contact patch and allow the remaining rubber to grip the surface of the road safely. However, using wet tires (with their channels) on a dry road provides less grip than a slick tire because some of the rubber surface area is absent due to the channels.
    Let assume we have worked out the Second Moment of Inertia and located the Axis of C.G.
    If I apply a lateral force at the point of C.G, both blocks should move the same distance at the same rate.
    I think you have pointed out that the "Real contact area" is the main factor here.
    Putting this into consideration and using the pressure formula (Pressure = Force/Area), than the force needed to move both the blocks should be the same, at least theoretically.
    Pressure will increase when the real contact area becomes smaller, therefore you will need more force to overcome the friction.
    When real contact area becomes bigger the pressure acting on the surface plane is still the same. It is just that the same amount of pressure is distributed over a bigger area.

    Therefore, in racing, it is not that tire with more thread will has less traction. Given that the pressure and load remain constant, that should not cause a difference in contact pressure between the tire and the road.
    In fact, they use the term hard and soft tire in F1 racing. Soft for dry land and hard for wet land.
    Last edited by Silence Sky; 17th June 2008 at 11:11 PM.

  16. #36

    Default Re: Bigger Tire Size is BAD and more dangerous.



    Here is how I look at hydroplaning.
    When the water is under the tire, it is not much of a concern becasue the thread grooves will channel the water away.

    When the tire hits a pool of water, you will experience a slow down in speed (decrease in velocity).
    When velocity comes to a sudden stop, the pressure will build up in front of the tire. The increase in pressure will then lift up the tire like a wedge. It is the same theory as how an air plane gets lifted up into the sky. Or you can imagine yrself trying to stop a flowing hose by plucking your finger into the hose, as you stop the water from flowing, do you feel the perssure acting on your finger?
    We are looking at a point of contact in the diagram. Can you imagine when the contact area gets bigger as you increase the width of your tire? You will have more pressure to lift up your tire.

    So bigger and wider tire than the normal spec given is no good, do you buy my points now?
    I bring this up bacause 9 out of 10 of my friends think that bigger tire has more traction and is safer.

  17. #37
    Member Knighthunter's Avatar
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    Default Re: Bigger Tire Size is BAD and more dangerous.

    Bigger tyre means bigger rim, lower profile. Lower profile means lesser deflection on the tyre wall --> Better Handling.
    Traction is also depend on the tyre compound and thread profile. Slick tyre will give the best traction on the dry track but it will be hydroplaning when the track is wet mean lesser traction and hard to control. This is proven the F1 car running faster on slick tyres compared to threaded (wet) tyre on dry track. Personally I am a fan of big rim and low profile tyre.

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