tire size...?

[pschaars951]

How do bigger wider tires help? does it give you more friction on the ground? Basic physics says no because you are dispersing the wieght over a larger area; so there is the same amout of friction as if you were on bicycle wheels... The only reason I can think of is that your tires would last longer.. but then they wouldnt put them on race cars would they?

I dont know; I am just confused.

-pete

[AMCPorsche924Powerhaus!]

wider tires don't allow the car to roll as muc ....better handling, flatter cornering...to a certain extent, if the tires are sticky sticky sticky ones, other wise yes the traction sucks.

If a formula one car had thin tires it would probably flip and roll over, although the old formula one cars did have like bike tires..lack of technology maybe.

And of course
taller tires get you better mileage....

bigger=longer distance for one RPM of your engine=better mileage, as long as you are within reasonable limits, because 100 " tires are going to suck up gas just to get them moving...

And higher speeds with taller tires can be gained.

(this is all assuming the wheel center to the outer part of the tire is bigger to what you are comparing too.)



[This message has been edited by AMCPorsche924Powerhaus! (edited 03-15-2001).]

[1.2gees]

Wider tires (of the same compound) do NOT provide more friction PER the same area, but they do overall, cause they provide the same amount of friction, over a larger area, thus overall friction (or traction when referring to tires' friction on the road) is higher.
Ahmet

------------------
It's all the driver...

[AMCPorsche924Powerhaus!]

If the car weighed 0 pounds then that would be correct.

[AMCPorsche924Powerhaus!]

think of when you roll a bike wheel around in teh garage compared to a fat car wheel (both with tires on it and pumped up)

Lean down on the bike wheel and try to spin it, hard to do, lean on the car wheel the same amount which is wider and its easyier to do, unless you have glue on the tires, which is basically what formula cars have.

[1.2gees]

That is not correct...

You do not increase the coefficient of friction (it's called Mu, if I remember right), so that's correct.

So it doesn't matter if you have 245/50/15s, or 225/50/15s, purely in friction provided per mm squared (for example).

And yes, the more weight you have, the more friction the tires will provide (though traction provided does NOT increase linear with weight increase).

However, let's say 200lbs on a tire, the wider the tire, the more grip it'll have, since it'll have more area, touching the road. In other words, more active friction area.

I should note that the area of the tire contacting the road would not go up, linear with the amount of weight that the given tire is loaded with.

For example, a 100mm wide tire, (let's just say) can provide 100lbs of force, in a certain direction, when loaded with 100lbs. A 200mm wide tire will provide less than 200lbs of force, when loaded with 100lbs.

Hope that clears it up a bit.
Ahmet

------------------
It's all the driver...

[AMCPorsche924Powerhaus!]

Ever watch a formula one race?
When the formula one car is on the grass, he can't get out, he's got motherly wide wheels, no traction.

On grass the sticky stuff on the tires doesn't work, so traction is critical to get out of grass, and a formal car can't do it.

If its soft grass....on hard grass they can get out.
And its not just because the car has tons of power.

[1.2gees]

Formula 1 car tires are NOT made to provide traction on grass!

It wouldn't matter how wide the tire is, they won't provide traction on grass.

I'm sure something A LOT thinner would work (better)on grass, but only because it can dig into the stuff. Which is not a concern, nor an issue on pavement. (which happens to be what the tires are designed for).

Also, formula 1 cars use racing slicks whenever it's not raining, these tires don't have tread, they're a continious piece of rubber... Ever think why? Well, to increase surface area (and reduce tread squirm, which is flexing of the rubber pieces, leading to more lean, and distracted feedback).
Ahmet

------------------
It's all the driver...

[AMCPorsche924Powerhaus!]

hehe

i never said formula one cars should have thin tires.

thats why they have sticky tires.
i never said they had tread either

sticky like glue, not groovy to cut into things.

[AMCPorsche924Powerhaus!]

oh yeah
hint: 100 pounds (lets say) on 5 cm squared (lets say), gives you more traction than 100 poounds on 7cm squared.

Its like pressure.
If I take a nail and put 100 grams on top of teh nail on your back and move the nail, your going to bleed (traction).
If I take a block of metal (same material as nail) and put the same mass on it (100g) and slide it along, there is no pain.

[1.2gees]

The nail's sharp end will dig into my skin (though it would take a lot more than 100grams to hurt me!), that's not friction, or traction. That's nail going through flesh, has just about nothing to do with a tire rolling on pavement...

Besides, the amount of pain I feel doesn't have anything to do with the amount of friction either. Pain isn't always linear with how much friction something provides!

You're looking at the wrong places for examples.

Consider this, I can apply more throttle with 255 section width Bridgestone Potenza RE-71s, than I could with 215s. With the same amount of weight on the tires, ditto for cornering.

More surface area=more traction, ON PAVEMENT, when digging into (or cutting into) is NOT an issue, with given amount of weight.

Is this helping at all?
Ahmet

------------------
It's all the driver...

[AMCPorsche924Powerhaus!]

i don't have the time to put it down in a formula just to prove myself right, i thought examples would be quick....
now what example can i use so you won't go to the diggin thing, lets see...

well one thing is, digging is a sign of traction.

Consider yourself skating. You are moving around a corner on your skates.
Put roller blades on.
BOOM you just fell on your ass on the ice.
Put skates on (smaller surface area touching ice)
You go around a turn. You glide around a turn.

Pavement is like ice, you need to try to dig into it, and if you don't (you can't)then you have good traction.

[AMCPorsche924Powerhaus!]

in fact the new downhill skiis out there, are very fat.

Fat skiis have less tractin when you are gliding, which makes you go faster when your skies are flat.

[AMCPorsche924Powerhaus!]

oh and longer skiis

longer skiis have more surface area.

In the Giant slalom and downhill races, you use longer skiis to go faster.
Control is a factor, but if smaller surface area was able to slide easier (what you are saying Ahmet) Then downhill racers would use the same size skis as the normal slalom racers do.

The same on more surface area makes you slide easier, which means your car is going to skid easier. (the skiier is the load)

When you are going downhill racing, you want the least traction, so more surface, longer skiis and wider, to the greatest extent before you get silly, because if you had too wide skiis you could not put them on you would hit and scrape your skiis and would have to do the splits down the hill just to move

Oh yeah and after we get this straight, the best thing you can do is get good tires, big wheels and good tires, good tires will overcome the need for smaller wheels to get traction, that is why formula one cars have very very very good tires, because there wheels need it.
Rubber is an elastic.

[This message has been edited by AMCPorsche924Powerhaus! (edited 03-15-2001).]

[1.2gees]

AMC, try and come up with a formula, from a reputable source. More surface area, keeping everything else constant will give you more traction, period.

Blades cut into the ice, and "trying to cut into the pavement" doesn't make any sense to me.

When tires are sliding, sometimes they "interlock" with surface irregularities, which's how they can have a coefficient of friction of over 1. (according to some research GoodYear did back in the late 70s).

Digging is NOT a sign of traction, it simply means the applied weight is too much for the given surface to support, without deforming.

You're giving me yet another example of a surface cutting through another one, or digging into it, with the skating example.

"Pavement is like ice, you need to try to dig into it, and if you don't (you can't)then you have good traction." I don't understand that statement, pavement is nothing like ice. Besides, you say that "you need to try to dig into it", then state that you cannot, and they you say that THIS is what provides traction.

I don't understand.

Again, if you can find a formula, to show relationship between weight on the tire, area of the contact patch, and the traction available (that would prove you right), go ahead and post it. If you like, I can post one that supports my idea, and cite it too. (I'm saying that with given weight on a tire, and assuming same compound for the tire, etc. more contact area = more traction available. Increasing weight on a tire will increase it's grip, but not linear to the weight increased).

I'd love to be proven wrong on this one!
Ahmet

------------------
It's all the driver...

[AMCPorsche924Powerhaus!]

oh and traction=not sliding you say...
well...the tire spinning around not moving is sliding, its just that its spining round and round because you are using a wheel.

If I put a dough roller on the counter and try to roll it, it slips, it won't roll without sticky dough.

If I put a dinky car down, it will roll the tires on the car.
smaller surface.

[This message has been edited by AMCPorsche924Powerhaus! (edited 03-15-2001).]

[AMCPorsche924Powerhaus!]

[This message has been edited by AMCPorsche924Powerhaus! (edited 03-15-2001).]

[AMCPorsche924Powerhaus!]

Ahmet, with no weight involoved, more surface is very very important for traction, yes, but a car has a very big weight....

Oh yeah and you stated about digging....

Its not that YOUR CAR is digging into the road

THE ROAD is digging into your tires.
Softer tires give you more traction, because the road is allowed to dig into the rubber more.

[This message has been edited by AMCPorsche924Powerhaus! (edited 03-15-2001).]

[1.2gees]

Static friction doesn't have much to do with the friction something provides when in motion.

Thus you should not (and can not accurately) compare the friction an object sliding against another provides, to the same object rolling on another object.

Static friction is usually much higher than (last time I looked into friction/traction/weight, etc. was a while ago, so bear with me) than active/kinetic friction.

That is it takes a lot more force for an object to start sliding, then it does to keep it sliding. A ski doesn't provide static friction, when in motion! Also, other factors are an issue, such as NOT to dig into the snow (which would slow you down, as you won't be sliding on it, rather going THROUGH it), as well as stability.

When one refers to traction, that's the friction a tire provides, when not locked up, typically with a low angle of slip as well.
Ahmet

------------------
It's all the driver...

[pschaars951]

ok this is my understanding of the physics of friction:

if you have 100lbs on a bike tire that has one square inch touching the ground; you have a certain amount of friction.

if you put 100lbs on a tractor tire with 100 square inches touching the ground you will have the same amount of friction as before, because the weight is less per square inch. So you have less friction per square inch, and when you add it up all the square inches they should equal the same as the bike tires friction.

whats wrong with my logic?

-pete