Thread by @DriveSmart_IN

Tyre Grip : A Thread 🧵

Recently,we saw so many accidents involving overspeeding on curves by overloaded vehicles,understeered vehicles resulting in fatal accidents etc.

Having a knowledge of tyres and how they work is essential to drive safely.

Tyres can do one thing to a maximum 100% efficiency. If they need to do two or more things then they have to share that ability. This is called tyre grip trade off. Therefore, if the vehicle is travelling in a straight line the front tyres need only steer.

Source : Roadcraft

If the vehicle needs to slow down then the tyres need only brake. If the vehicle is on a curve and you need to apply the brakes then clearly the tyre has to do two things - steer and brake. This means it cannot do either to maximum efficiency.

If the speed is such that the tyres are starting to squeal then they are starting to lose grip. Application of more steering usually results in total loss of directional control.

As more tyre grip is used for braking, there is less grip available for steering and vice versa.This reduces your control over the best positioning for the hazard.

Hence, controlling your vehicle depends on how well you use the tyre grip available for steering and turning.

The patch of tyre that is in contact with the road is normally the size of the human palm ✋
The size varies with tyre size, inflation levels etc.
Now imagine your car with your family on highway at 120 km/h,and realize that its grip on road depends on four little palms.

Also,the tyre contact size with road changes with speed, braking, turning as weight shifts to front while braking,shifts to rear while accelerating and shifts to left or right while we are turning.
Source : Roadcraft

The tyre contact patch with the road while accelerating is shown here.
As seen below, as we speed, contact reduces on front tyres.

This shows the amount of tyre contact while braking and turning.
As seen below,as we brake,the weight pushes forward.

As we increase speed,the tyre grip reduces further.
As seen below,as the speed increases and with poor tyres,the grip reduces even further.
Now,if we speed on a curve,the amount of grip is already less and the less grip needs to be shared for turning and braking, causing a crash

How to handle it?
Braking or speeding as we turn on a curve will use more tyre grip for braking and less for steering.
This forces Vehicles to either understeer/oversteer.
💡🧠
So,reduce speed before entering curve.
Use available grip for steering and accelerate as you exit curve

Have sufficient inflated tyres as per the owner's manual.
As seen below, underinflated tyres reduces tyre grip even further.
And if we speed,the grip will reduce even further.
And if we turn on a curve at speed,just imagine the available grip 😮😮

Technologies like ABS,ESP, traction control helps to mitigate the risk but don't depend on technology alone as it has its own limitations.
It's our duty as a driver to reduce the triggering of certain conditions which hits the limits of any technology or material.

To conclude:

1. Have sufficient inflated tyres as per recommendation.
2. Check tyre tread regularly and change old tyres.
3. Reduce speed before entering a curve.
4. Use the tyre grip for steering on curve.
5. Accelerate as you exit the curve.
Now we don't make these mistakes

How to handle if vehicles from the opposite side don't follow the same and come head-on to you?
Can we reduce some risks?
We will discuss that in the next Thread.


@RSGuy_India @Team_Road_Squad @TopDriverIndia @ReduceRoadRisks

And do not overload vehicles beyond the required capacity.
As weight impacts braking and other aspects as we discussed above.

A 5 seater car means 5 adults. That's it.
@InsAdmnHYDTP @IamLokendra_
@rkntwia