F=uR...Why do wider tires grip better?

[289Notch]

The weight of the car is constant, but the forces on each tire varies. For instance, in cornering, the weight tranfers to the outside tires. Once one of the outside tires breaks free, it's all over.

I said RATHER constant. just trying to simplify for the concept.

[PHRANQUY]

think about tractor pulls. those 4x4 truck pulls have decently wide tires.

I've seen a lot of them run dual (Or more in one case) front/rear tires even.

[Scorpner]

I said RATHER constant. just trying to simplify for the concept.

Sorry, I misunderstood what you meant.

[Steve]

What he's trying to say is PRESSURE P=F/A where F=Force and A=Area of tread on contact patch.

but force is not a variable here. Our vehicles weight is rather constant. So we vary the area of the contact patch. rubber on ice there is very little adhesion so we need to maximize the pressure by minimizing the area. (this is for static frictional cases where tire doesn't slip) once the tire slips the dynamic friction is very very small and ur fvcked.

OK, why would ice be any different than any other hard surface? I can see why a narrow tire would work better on dirt, because you need to dig down to the hard surface. Why is narrower better on ice? Are you assuming studs need to dig in or what?

[ScotWithOne_t]

I would imagine a wide tire would actually be better on glare ice, since ice melts under pressure, forming a layer of water between the tire and the top of the ice, similar to how ice-skates and skis work. But in snow, I'd say the same principal as dirt applies so skinnier = better. I'm just theorizing here...I have no experience with ice racing.

[PHRANQUY]

Ice doesn't behave like other surfaces do. You could have a nice Mud Terrain tire that grips great in mud, dirt, snow... rocks... but unless they are siped, they won't do you any good. The problem with ice is that tires rely on friction for traction, and friction causes heat, which then melts the ice. The water acts like a lubricant on the ice and the tire can not achieve traction. So at that point not only do you have a low-friction surface, but you have a low-friction surface wit ha lubricant on it.

I've been researching this quite a bit because i want a Mud Terrain tire for the Heep that would be good for daily driving, but have only found 3 tires that might work... Interco (SuperSwamper) Trxus MT, Nitto Mudd Grappler, and one other that I can't thik of right now.

[1moretoy]

OK, why would ice be any different than any other hard surface? I can see why a narrow tire would work better on dirt, because you need to dig down to the hard surface. Why is narrower better on ice? Are you assuming studs need to dig in or what?

Pounds per square inch. The weight of the vehicle is dispersed over a greater area which in my mind equal's less friction or pounds per square inch on the surface. It's almost as if the vehicle is floating. Switching to a narrower tire is like adding weight to the vehicle by putting a greater force in the surface. again pound per square inch. I speak from owning a single rear wheel truck and now owning a dually. The SRW will out perform the DRW in any situation do to the contact area being is so much greater.

Non of this probably makes any sense to some of you but I just had to say something based my experiences in a limited traction situation's.

[Southern]

Pounds per square inch. The weight of the vehicle is dispersed over a greater area which in my mind equal's less friction or pounds per square inch on the surface. It's almost as if the vehicle is floating. Switching to a narrower tire is like adding weight to the vehicle by putting a greater force in the surface. again pound per square inch. I speak from owning a single rear wheel truck and now owning a dually. The SRW will out perform the DRW in any situation do to the contact area being is so much greater.

Non of this probably makes any sense to some of you but I just had to say something based my experiences in a limited traction situation's.

Huh?

[1moretoy]

Huh?

Exactly

[Mullet Tuner]

Here are some average coefficients of friction for different surfaces...

Asphalt (dry) Peak=.9 Sliding=.8
(wet) Peak=.6 Sliding=.5

Concrete (dry) Peak=.9 Sliding=.8
(wet) Peak=.8 Sliding=.7

Snow (hard packed) Peak=.2 Sliding=.15

Ice Peak=.1 Sliding=.07

[Steve]

Pounds per square inch. The weight of the vehicle is dispersed over a greater area which in my mind equal's less friction or pounds per square inch on the surface. It's almost as if the vehicle is floating. Switching to a narrower tire is like adding weight to the vehicle by putting a greater force in the surface. again pound per square inch. I speak from owning a single rear wheel truck and now owning a dually. The SRW will out perform the DRW in any situation do to the contact area being is so much greater.

Non of this probably makes any sense to some of you but I just had to say something based my experiences in a limited traction situation's.

This contradicts everything we've discussed in this thread thus far.

Force over Area equals pressure but does not equal friction. Friction is the coef of friction of a particular material multiplied by the weight of the object. Nowhere in the Friction formula is area accounted for.

Here are some average coefficients of friction for different surfaces...

Asphalt (dry) Peak=.9 Sliding=.8
(wet) Peak=.6 Sliding=.5

Concrete (dry) Peak=.9 Sliding=.8
(wet) Peak=.8 Sliding=.7

Snow (hard packed) Peak=.2 Sliding=.15

Ice Peak=.1 Sliding=.07

I am surprised wet concrete offers this much grip. Where did you pull that from?

[Miekk]

Pounds per square inch. The weight of the vehicle is dispersed over a greater area which in my mind equal's less friction or pounds per square inch on the surface. It's almost as if the vehicle is floating. Switching to a narrower tire is like adding weight to the vehicle by putting a greater force in the surface. again pound per square inch. I speak from owning a single rear wheel truck and now owning a dually. The SRW will out perform the DRW in any situation do to the contact area being is so much greater.

Non of this probably makes any sense to some of you but I just had to say something based my experiences in a limited traction situation's.

Given that argument, my tractor can't pull anything...

[KickAssFlash]

I like that tractor. Thats a nice tractor.

[Miekk]

I like that tractor. Thats a nice tractor.

It's a traction tractor, it has a lot of traction but yet very little pounds per square inch. Worthless on the ice though..

I've got a Bully Dog chip in it.. up 30%.

[Mullet Tuner]

This contradicts everything we've discussed in this thread thus far.

Force over Area equals pressure but does not equal friction. Friction is the coef of friction of a particular material multiplied by the weight of the object. Nowhere in the Friction formula is area accounted for.




I am surprised wet concrete offers this much grip. Where did you pull that from?

They were presented in my chassis engineering class.