Friction & Tyres: Why Thicker Car Tyres Give Better Grip

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Discussion Overview

The discussion revolves around the relationship between the thickness of car tyres and their grip on the road, particularly examining the principles of friction and the materials involved. Participants explore theoretical and practical aspects of friction, including its dependence on surface area and material properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that friction is independent of the area of contact and depends solely on the materials involved.
  • Others propose that thicker tyres, often made of softer rubber, provide better grip due to their material properties, despite the theoretical friction law.
  • A participant questions how thicker tyres can compensate for increased wear if they are made of softer rubber, suggesting a potential contradiction in the argument.
  • One contributor highlights that the friction law may not apply to tyres in real-world conditions, where surfaces are not smooth and dry.
  • Another participant mentions that if friction is not between the tyres and the road, it could involve interactions with materials between the tyre and the road, which may also adhere to the principle of area independence.
  • A later reply introduces the concept of tire load sensitivity, suggesting that thicker tyres reduce load per unit area, which may influence grip.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the friction law to tyres, with some agreeing on the independence of area in ideal conditions, while others argue that real-world factors complicate this relationship. The discussion remains unresolved regarding the implications of tyre thickness on grip and wear.

Contextual Notes

Participants note limitations in applying theoretical friction laws to practical scenarios, emphasizing the need to consider real-world conditions and material properties.

jablonsky27
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Friction between 2 surfaces is independent of the area of contact and depends only on the nature of the two materials right?
Then why do thicker car tyres give better grip?
 
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Because they are made of softer rubber. To make up for the greater wear you have to have more of it to give a reasonable life.
Good question - most people don't really believe the law about friction being independent of area!

On motorbike tyres there are also secondary effects, you want a larger size to make sure that the entire contact path isn't resting on the same pit of gravel.
 
Why does softer rubber grip better?

If thicker tyres are made of softer rubber, then won't the diameter of the tyres reduce faster? So how does having more rubber make up for greater wear and tear?
 
You can not apply the friction law to the case of tires totally. To have the formula F=u*P (without area), the surface must be very smooth and dry.
You tires and the road surfase probably are not in that ideal condition.
 
If its not friction between tyres and the road, it ll be friction between the tyre and something between the tyre and the road.. In any case, that friction too will be independent of area..
 
jablonsky27 said:
Friction between 2 surfaces is independent of the area of contact and depends only on the nature of the two materials right?
Not in the real world, only in an idealized situation.
Then why do thicker car tyres give better grip?
Because of tire load sensitivity, thicker tires reduce the load per unit area:

http://en.wikipedia.org/wiki/Tire_load_sensitivity
 

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