Re: 4ksq Tires and Suspension Questions

["Martin Pajak" <quattro@rogerswave.ca>]

> >Most common mistake people make is they assume that a wider tire
> >makes larger contact with the pavement.  That is not the case.  Even
> >if you get 255's they will still have the same contact area as 195's.
> >Simple physics dictates the rules.  The reason you want the wider tire
> 
> Uh, show me the physics.  a 245 will to put more rubber on the road.  I
> am not following you on this one,
> where are you getting your "Phisics info"  A larger tire has more air in
> it to compress yes, but the width greatly out weighs the difference in
> front to back contact area.

The larger tire will have more air in it that's true.  But it will 
usually have the same pressure as the samaller tire (depending on the 
car usually between 23 - 44 psi).
The same pressure means that for a given load the tire will have to 
have a certain area.  Same load / same pressure = same area of 
contact (given by pressure = load / area).  
When the tires width increases the length of contact across the tire 
increases therefore decreasing the contact length along the tire 
(direction of rotation) to make the same area .  
This is why a wider tires tread block will not heat up as quickly 
as smaller tires simply becouse it spends less 
time in contact with the road as the tires is spinning.

HTH
 

Martin Pajak
quattro@rogerswave.ca
http://www.geocities.com/MotorCity/5939

1982 Coupe TURBO (473,150 km)
1984 4000s quattro (soon to be a rally car)
1986 4000s quattro (326,000 km) 
1982 Coupe (154,000) parts car

CEO of exam lastminute allniter rollthedice inc.