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Tyre Profiles


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#1 hairy

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Posted 13 July 2019 - 10:53 PM

I thought this was an interesting observation from Siztenboots:

 

http://www.vx220.org...sale/?p=1977569

 

Why do rear wheels have much higher profile than fronts? I know it works better, but why.( I don't think this is exclusive to VX220)

 

Sorry for being a numpty, I wouid like to understand the physics at play.



#2 Nev

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Posted 14 July 2019 - 04:27 AM

Do you remember when I borrowed your wheels Hairy? It was to test how the higher profile front tyres affected the car.

 

My conclusion is the front of the car is better with higher profile tyre. I think this is mainly due to the low axel weight over the front (42%), so the front tyres grip better when the tarmac is ripply or uneven when they have the . The compliancy of a higher profile (with more sidewall flex to adjust to varying camber, more air to absorb small bumps etc) helps when there isn't much weight over the axel (particularly when accelerating, when the weight on the front axel might drop to just 20% on a VX220).

 

 

 


Edited by Nev, 14 July 2019 - 04:35 AM.


#3 aquilaproejct

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Posted 14 July 2019 - 11:32 AM

Rears are smaller profile (sidewall as a % of width). You are trying to get rolling diameter the same front and rear. For the same diameter rim a wider (rear) tyre will have smaller profile than a skinny front.




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