[Land-speed] Contact patch size

[Doug Odom]

Jon, Anytime you are thinking or talking about race tires first you have to 
understand. It makes all the difference in the world if you are talking 
about a radial tire or a bias belted tire. Having spent many days in the 
shop with a car on four scales, changing tire pressure and sizes and load 
and having been on many stock car tire tests with Goodyear and a lot more 
with the old Firestone stock car tire I can tell you most of the time what 
works with radial tires makes bias worse handling. What you see and hear on 
the TV at the nascar races in no way will work on LSR tires. They change air 
pressure to change the spring rate of that corner of the car. Changing 2 
lbs. of air in a radial will not change the foot print very much at all but 
it will change the spring rate a bunch. You would not even feel it in a 
straight line but in the corner you sure would.     Just my 2 cents 
Doug in big ditch

>
> Neil and all the rest of you:
>
> Good - lots of responses.  First of all -- I want a very simple  contact 
> patch -- one that doesn't include things such as sand or snow  where the 
> surface material might get up and between bits of the tread  pattern.  I'm 
> talking about flat rubber contacting flat surface (be  that pavement or 
> salt or ice).
>
> I'm also disregarding the concept of traction that's available (ice is 
> slippery compared to concrete compared to salt, etc).  I'm only  talking 
> square inches contacting a flat surface.
>
> I hope you understand that I realize that a softer tire will likely  flex 
> more and thereby will probably generate more heat.  I don't care  about 
> that in this argument -- I only want to talk about the absolute  size of 
> the contact patch.
>
> Different tire materials are also irrelevant -- in that it'll take  just 
> as many square inches of air-inflated rubber as it will air- inflated 
> nylon or Kevlar or whatever.  A hard tire (concrete or wood,  for example) 
> would not flex and therefore isn't of interest here.
>
> I will say that Mayf's comments is good -- that is, a high pressure 
> inside the tire will translate to high pressure between the tire and  the 
> surface, and that can be assumed to offer an opportunity for  higher 
> traction.  And also -- narrow can be better for traction for 
> hydroplaning, of course -- just like it is when driving in snow ("cut 
> through the water/snow rather than float over it").
>
> Back to you. . .
>
>       Jon Wennerberg
> Tall guy with moustache
> and a pair of 2 Club hats
> _______________________________________________