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Author Topic: Why would car tyres dry at different rates?  (Read 1588 times)

Offline thedoc

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Why would car tyres dry at different rates?
« on: 18/09/2012 05:30:02 »
John Allen asked the Naked Scientists:
   
Hi can you please answer a question for me,

"Why after a journey in the wet are the front tyre walls dry and the rear ones still wet?" I have looked at both rear and front wheel drive cars and it appears to be the same with either cars.


Thanks

John Allen
(Norwich)

What do you think?
« Last Edit: 18/09/2012 05:30:02 by _system »


 

Offline CliffordK

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Re: Why would car tyres dry at different rates?
« Reply #1 on: 18/09/2012 07:25:28 »
Odd, I hadn't noticed that. 

It is possible that the disk brakes transfer more heat to the front wheels than the drum brakes in the rear, but I would look elsewhere for the solution.

I would think that the airflow patterns would bring more dry wind and less roadspray to the front tires, and the rear wheels would get more roadspray, as well as being more protected from the wind flow.
 

Offline wolfekeeper

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Re: Why would car tyres dry at different rates?
« Reply #2 on: 18/09/2012 12:57:53 »
Yes, it's probably mostly the brakes.

Cars brake mostly using their front brakes, because when you brake the weight transfers to the front, which gives the front tyres a lot more grip.

If you were to brake with all four wheels the same amount, the back would always skid first (which is very undesirable, the car would spin very easily). Most cars have a device called a brake apportioning valve that has a lot to do with this; under light braking they're all used, but more front brakes are used under heavier braking.

So cars use the front brakes a lot more, and that will heat up the wheels and tend to dry the tyres.
 

Offline grizelda

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Re: Why would car tyres dry at different rates?
« Reply #3 on: 18/09/2012 20:36:07 »
Plus the work of steering probably heats up the tyres.
 

Offline damocles

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Re: Why would car tyres dry at different rates?
« Reply #4 on: 21/09/2012 13:05:31 »
plus the front tyres probably throw up a lot of surfactant road scum which lands on the rear tyres
 

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Re: Why would car tyres dry at different rates?
« Reply #4 on: 21/09/2012 13:05:31 »

 

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