[Land-speed] Contact patch size

Jon Wennerberg jonwennerberg at nancyandjon.org
Mon Nov 17 17:50:57 MST 2008


On Nov 17, 2008, at 6:58 PM, Doug Odom wrote:

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



I'll grant you that handling and myriad other issues can and are  
affected by changing tire pressure and construction and such -- but my  
question is simply about the pressure of the air in the tire, the  
weight on the tire, and the resulting amount of contact patch.

I realize one big caveat about patch applies when we're talking about  
big-ass slicks on a dragster - slicks that run very low pressure and  
are heated and treated with stickum -- so that the tire can deflect  
under extreme acceleration and have more of the sticky tire sticking  
to the race track.  Go back to static loads -- tires not rotating,  
vehicle not moving.  That's where my question is meant to be.

Boyoboy, this is fun -- we haven't had this much discussion in a few  
days (maybe longer).  Thanks to one and all for giving me something to  
think about while I was on the snowthrower today -- moving the FOOT of  
snow we got since this time last night.  And - for what it's worth --  
I not only run low pressure in the tires on the tractor -- but tire  
chains, too.  Snow is NOT the ideal surface I'm mentioning in my  
question.


       Jon Wennerberg
Tall guy with moustache
and a pair of 2 Club hats


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