# Wider tires experience more friction than narrow tires?

## Homework Statement

"Cars with wide tires experience more friction than cars with narrow tires"

## Homework Equations

Is that statement true or false?
What are the advantages of wider tires? explain!

## The Attempt at a Solution

I think that they experience the same friction because they will still have the load of the car above them. Even though they are a bit wider it won't make a difference :\

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Well, if friction is caused on the microscopic level by bonds made between the material of the tire and the material of the ground, it would stand to reason that wider tires give more surface contact and thus more friction.

That being said, I am not 100% about this and would love confirmation or a reason why this is not so.

Well, if friction is caused on the microscopic level by bonds made between the material of the tire and the material of the ground, it would stand to reason that wider tires give more surface contact and thus more friction.

That being said, I am not 100% about this and would love confirmation or a reason why this is not so.
uhh can you please put that in a little bit easier words, im only in grade 11 lol and its my first physics class :\
All i know is Static Friction, forces (Normal force, applied force, friction force, force of gravity) and i know Kinetic friction a bit. Also the 3 newton laws.
thanks

bcrowell
Staff Emeritus
Gold Member
Physics textbooks typically present a mathematical model of friction. You need to use that.

I was always under the impression that friction "is" the overcoming of molecular bonds made between (in this case) the tires and the ground. The tires and the ground form bonds much like atoms do to form molecules. It takes energy to overcome these bonds and it takes energy to overcome the bonds formed between the rubber in the tires and the asphalt in the ground.

So, it stands to reason, the more bonds formed (due to more surface contact), the more the friction is.

The standard physics textbook definition for the magnitude of friction only deals with the weight, not the surface area. But, as I said, I am not sure if this is 100% true beyond the standard first high school/college look.

Fr = μN

where:

* Fr is the resistive force of friction
* μ is the coefficient of friction for the two surfaces (Greek letter "mu")
* N is the normal or perpendicular force pushing the two objects together
* μN is μ times N

surface area doesn't come into it.

Physics textbooks typically present a mathematical model of friction. You need to use that.
Well my teacher isn't expecting a mathematical answer. He just wants a conceptual answer as to why this is the case (If its true) and what the advantages are in wider tires. I've heard different opinions which seem to be sometimes completely opposite of each other and im wondering what is right

I just checked Wikipedia. The formula given in textbooks (as quoted above) is an approximation.

In actuality, surface area does matter, which is why racing car tires are wider.

In actuality, surface area does matter, which is why racing car tires are wider.
Not only wider but no ridges, so it is smooth and therefore more road contact.

Well for your answer I'd quote the formula, explain how surface area isn't a factor, but then counter argue and say how this formula is only an approximation and surface area does matter.