Fat tires work better not because of increased friction

[Vic]

Originally posted by: smack Down
Umm you are complete wrong if you think the width of a tire has no effect on the size of the contact.

Do please elaborate. I would love to hear your argument about how -- all else being equal (vehicle weight, tire pressure, etc.) -- the width of the tire can effect the area of the contact patch.

 

[MichaelD]

*tsk* Let me help you n00bs with the physics equation.


F/U=contact patch*sphincter factor/square of F/U.

So, we can say that if you are FU'd b/c your sphincter was too loose and you weren't cautious enough, then you wrap the car around a tree and you are FU'd...in a square.

Yeah.

 

[sao123]

Originally posted by: virtualgames0
My physics professor claims that surface area has nothing to do with friction.
So then what makes fat tires more effective?

ask him if you can replace his cars brake pads with the ones off a bicycle tire...
see what he says.

 

[Vic]

Originally posted by: sao123

Originally posted by: virtualgames0
My physics professor claims that surface area has nothing to do with friction.
So then what makes fat tires more effective?

ask him if you can replace his cars brake pads with the ones off a bicycle tire...
see what he says.

Unlike a tire, brake pads are not designed to be a near-perfect circle, with the contact patch created solely by the weight of the vehicle and the air pressure inside the tire.

 

[Rubycon]

Global warming is going to make all your motorcars obsolete!

:laugh:

 

[Triumph]

It's simple. Mu is different for wider tires. Problem solved. Now your friction force is higher.

 

[Perknose]

Fat tires are like fat chicks. You have to keep them properly inflated.

 

[msparish]

Originally posted by: virtualgames0

Originally posted by: Vic

Originally posted by: CombatChuk
With wider tires you don't get a bigger contact patch, you change the shape. Wider tires will have a contact patch that wider itself but the area will stay the same

This is correct. The area of the contact patch is determined by the air pressure in the tire, the hardness of the rubber compound, and the weight of the vehicle.
Tire size, skinny or fat, determines the shape of the contact patch, not the area. It is the wider shape of the contact patch that makes fatter tires more effective in cornering. Note that dragsters have skinny tires, those are more effective for straight-line acceleration.

It still seems like the tire width would serve as a coefficient for the contact patch.
Say 20psi gives allows 1cm of tire to make contact with the road. If the tire is 10cm wide, it would have an area of 10cm². If the tire was twice as wide, 20cm, it would have an area of 20cm².

You're wrong. In either case you'll have the same contact area. With the wider tire, the contact area will be wider, but thinner.

 

[hoorah]

Originally posted by: Perknose
Fat tires are like fat chicks. You have to keep them properly inflated.

No no no,

Fat chicks are like mopeds. They're sorta fun to ride around, but you're embarassed when your friends see you on one.

 

[DrPizza]

I'm in a hurry and don't have time to read through the posts. But, your professor is right. Friction is independent of surface area. However, there are other things involved with tires on roads. Traction isn't exactly the same thing as friction. Someplace, I was involved in a lengthy detailed discussion with people I'd consider more expert on the matter... it was either on a physics teachers/professors listserv, physicsforums.com, or in the highly technical area here.

If you need a really good explanation, just go over to physicsforums.com, and search the archives there or post a question there. It's actually quite an interesting question to explore.

 

[Tom]

Originally posted by: msparish

Originally posted by: virtualgames0

Originally posted by: Vic

Originally posted by: CombatChuk
With wider tires you don't get a bigger contact patch, you change the shape. Wider tires will have a contact patch that wider itself but the area will stay the same

This is correct. The area of the contact patch is determined by the air pressure in the tire, the hardness of the rubber compound, and the weight of the vehicle.
Tire size, skinny or fat, determines the shape of the contact patch, not the area. It is the wider shape of the contact patch that makes fatter tires more effective in cornering. Note that dragsters have skinny tires, those are more effective for straight-line acceleration.

It still seems like the tire width would serve as a coefficient for the contact patch.
Say 20psi gives allows 1cm of tire to make contact with the road. If the tire is 10cm wide, it would have an area of 10cm². If the tire was twice as wide, 20cm, it would have an area of 20cm².

You're wrong. In either case you'll have the same contact area. With the wider tire, the contact area will be wider, but thinner.

it isn't that simple in the real world. And even if you are correct, a wider but thinner contact patch would resist forces applied sideways better than a skinnier one.

like the difference between breaking a pencil in half along it's length is very easy, along it's dimaeter is virtually impossible.

 

[Trikat]

Fat tires wouldn't matter if cars could fly. (Stupid rush hour).

 

[Ika]

Originally posted by: Trikat
Fat tires wouldn't matter if cars could fly. (Stupid rush hour).

Like that new GM commercial?

 

[tboo]

Fat tires suck in the snow

 

[cavemanmoron]

if your on pavement, or sand,
wider shorter profile tire works better;
partly because the cg is lower.


On snow covered roads, a tall skinny tire is often better,
especially if its a Studded Snow tire.

 

[AgaBoogaBoo]

Originally posted by: cavemanmoron
if your on pavement, or sand,
wider shorter profile tire works better;
partly because the cg is lower.


On snow covered roads, a tall skinny tire is often better,
especially if its a Studded Snow tire.

I was waiting for that second statement to show up in this thread

 

[Oscar1613]

Originally posted by: virtualgames0

Originally posted by: Vic

Originally posted by: CombatChuk
With wider tires you don't get a bigger contact patch, you change the shape. Wider tires will have a contact patch that wider itself but the area will stay the same

This is correct. The area of the contact patch is determined by the air pressure in the tire, the hardness of the rubber compound, and the weight of the vehicle.
Tire size, skinny or fat, determines the shape of the contact patch, not the area. It is the wider shape of the contact patch that makes fatter tires more effective in cornering. Note that dragsters have skinny tires, those are more effective for straight-line acceleration.

It still seems like the tire width would serve as a coefficient for the contact patch.
Say 20psi gives allows 1cm of tire to make contact with the road. If the tire is 10cm wide, it would have an area of 10cm². If the tire was twice as wide, 20cm, it would have an area of 20cm².

you're thinking about this wrong. P = F/A or A = F/P. if you change tires, the force (weight of car) stays approximately the same and you keep the tires at same pressure, then the area must be the same as well. it can change shape, but not size.

 

[yhelothar]

Originally posted by: Oscar1613

Originally posted by: virtualgames0

Originally posted by: Vic

Originally posted by: CombatChuk
With wider tires you don't get a bigger contact patch, you change the shape. Wider tires will have a contact patch that wider itself but the area will stay the same

This is correct. The area of the contact patch is determined by the air pressure in the tire, the hardness of the rubber compound, and the weight of the vehicle.
Tire size, skinny or fat, determines the shape of the contact patch, not the area. It is the wider shape of the contact patch that makes fatter tires more effective in cornering. Note that dragsters have skinny tires, those are more effective for straight-line acceleration.

It still seems like the tire width would serve as a coefficient for the contact patch.
Say 20psi gives allows 1cm of tire to make contact with the road. If the tire is 10cm wide, it would have an area of 10cm². If the tire was twice as wide, 20cm, it would have an area of 20cm².

you're thinking about this wrong. P = F/A or A = F/P. if you change tires, the force (weight of car) stays approximately the same and you keep the tires at same pressure, then the area must be the same as well. it can change shape, but not size.

I may be thinking about it wrong.. but yours doesn't seem right either. The P in your equation is not the pressure in the tire, but the pressure of the tire in contact with the ground.

 

[kingtas]

My wife's narrow tires did better than my wide tires in the snow.

 

[Oscar1613]

Originally posted by: virtualgames0

Originally posted by: Oscar1613

Originally posted by: virtualgames0

Originally posted by: Vic

Originally posted by: CombatChuk
With wider tires you don't get a bigger contact patch, you change the shape. Wider tires will have a contact patch that wider itself but the area will stay the same

This is correct. The area of the contact patch is determined by the air pressure in the tire, the hardness of the rubber compound, and the weight of the vehicle.
Tire size, skinny or fat, determines the shape of the contact patch, not the area. It is the wider shape of the contact patch that makes fatter tires more effective in cornering. Note that dragsters have skinny tires, those are more effective for straight-line acceleration.

It still seems like the tire width would serve as a coefficient for the contact patch.
Say 20psi gives allows 1cm of tire to make contact with the road. If the tire is 10cm wide, it would have an area of 10cm². If the tire was twice as wide, 20cm, it would have an area of 20cm².

you're thinking about this wrong. P = F/A or A = F/P. if you change tires, the force (weight of car) stays approximately the same and you keep the tires at same pressure, then the area must be the same as well. it can change shape, but not size.

I may be thinking about it wrong.. but yours doesn't seem right either. The P in your equation is not the pressure in the tire, but the pressure of the tire in contact with the ground.

the pressures have to be equal otherwise you'd be riding on the rims

 

[CombatChuk]

Originally posted by: kingtas
My wife's narrow tires did better than my wide tires in the snow.

That's because the narrow contact patch was able to "cut" through the snow...

 

[Howard]

http://www.autozine.org/technical_school/tech_index.html#Handling

 

[yhelothar]

Originally posted by: Howard
http://www.autozine.org/technical_school/tech_index.html#Handling

:thumbsup:
awesome site..
I'm gonna be stuck on there for a while now.

 

[smack Down]

Originally posted by: Oscar1613

Originally posted by: virtualgames0

Originally posted by: Oscar1613

Originally posted by: virtualgames0

Originally posted by: Vic

Originally posted by: CombatChuk
With wider tires you don't get a bigger contact patch, you change the shape. Wider tires will have a contact patch that wider itself but the area will stay the same

This is correct. The area of the contact patch is determined by the air pressure in the tire, the hardness of the rubber compound, and the weight of the vehicle.
Tire size, skinny or fat, determines the shape of the contact patch, not the area. It is the wider shape of the contact patch that makes fatter tires more effective in cornering. Note that dragsters have skinny tires, those are more effective for straight-line acceleration.

It still seems like the tire width would serve as a coefficient for the contact patch.
Say 20psi gives allows 1cm of tire to make contact with the road. If the tire is 10cm wide, it would have an area of 10cm². If the tire was twice as wide, 20cm, it would have an area of 20cm².

you're thinking about this wrong. P = F/A or A = F/P. if you change tires, the force (weight of car) stays approximately the same and you keep the tires at same pressure, then the area must be the same as well. it can change shape, but not size.

I may be thinking about it wrong.. but yours doesn't seem right either. The P in your equation is not the pressure in the tire, but the pressure of the tire in contact with the ground.

the pressures have to be equal otherwise you'd be riding on the rims

Umm no they don't the air pressure is almost completely independent form the pressure on the road.

 

[smack Down]

Originally posted by: Vic

Originally posted by: smack Down
Umm you are complete wrong if you think the width of a tire has no effect on the size of the contact.

Do please elaborate. I would love to hear your argument about how -- all else being equal (vehicle weight, tire pressure, etc.) -- the width of the tire can effect the area of the contact patch.

The contact patch depends on how much the sidewall deforms. All else being the same then the two tires will have a the same deformation of the sidewall and the wider tire will have a greater contact patch.