1. why are the tyres of racing car wide?2. direction of friction on two tyres of bicycle and why?

1st Question Answer is

Two things racecar tires have to worry about with that your family car tire does not.

1. Heat dissipation and rubber melting rate, racecars want the rubber to melt a little, but not too much.

2. Stiffness, they want very soft rubber, but they don''t want it to deform under acceleration, turning and braking so a way to prevent it is increasing the width.


Race car tires are much wider – up to 12 inches wide in the front and 16 inches wide in the rear, whereas the typical passenger car tire is seven to nine inches wide.

The reason they are wide is to increase stiffness so that during acceleration, turns and braking, the amount of rubber touching the road does not decrease too much.

Racecar tires use rubber that is much softer than rubber on cars. It is more like a soft rubber eraser than anything else, and very unlike the hard rubber found in passenger car tires. Since they use very soft rubber it tends to melt during the race, which makes the rubber even stickier than before.

Contrary to intuition, the large width of a racecar tire does not increase the frictional force available to it by itself. If you take your own car and put in tires that are 3 feet wide made of the same kind of rubber, you will not get better grip onto the road.

The reason for this is because as you increase the surface area of the tire, the weight pushing down on a rubber particle decreases. At the macroscopic level, as you increase the surface area touching the ground, the rubber/glue particles break contact with the road and hover over the road instead of touching because there is less force pushing on every rubber particle.

So ultimately the amount of rubber molecules making contact with the road particles are not increased when you use a larger or wider tire on a vehicle with the same weight.

Most race cars have slicks that is a tyre with no tread for maximum grip in the dry. then there is a medium tyre which has a little tread for damp conditions, and there is a tyre called wets which have a lot of tread for raining conditions

2nd Question Answer is

The bicycle''s tires are both moving in the anticlockwise direction so the friction is in the clockwise direction.......

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