[dad]

tdot-zx3,Mar 19 2005, 02: Wrote:

ANTHONYD,Mar 18 2005, 01:55 PM Wrote:Does the size of the area of tire making contact with the road play an important part in oversteer?

When your talking about tires and asking a question like that its difficult to answer because your dealing with whatever coefficient of friction a tire has... Which is going to change from car to car. Temperature, Slip, Pressure, Loading and obviously factors generated by size, width and surface area driving on.

Temperature wise, what your asking could happen if.... The rwd car was driving fast down a straight away say, and the rear tires were working hard while the front ones had little stress on them. The rear tires would stay heated, while the fronts would be cooler. If a turn came and instead of breaking you lifted from throttle, the front tires would be cooler until warmed from the turn, and *should* understeer until doing so. If at another turn you had to braked hard first, the front tires would heat up, allowing them to have better traction pulling the car through the turn. Basically, tires are always going to grip more as they heat up, if this setup with stretched tires effects heat in any way then possibly it could.

Slip is the relationship between the slipping of the tire and the coefficient of friction... When you brake, turn, accelerate, your tires are always slipping here and there. An extreme would be like, slamming on the brakes and you just keep sliding. Anyways ... maximum traction comes at somewhere around 5degrees of slip, thats all thats really important to know. If tires are mixmatched front and back, installed differently or whatever the changes in degrees of tire slip can affect and even cause oversteer/understeer.

Bare with me its not the most technical explination... But it is almost 3am. Ive read some great books on tire subjects and the likes... someone please correct me if my brain has mixed something up but that should be right and give you a little insight to your question.
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Dan...This line of tech is kinda one step up from the tire streching issue...The basis of this tech when expanded upon is really quite correct based on any of the reading I have done and experiences I have had....Having said all that , and if someone could simplifie what your saying, slip factors are no doubt the biggest consideration for tire selection....But what you got to remember is even if you were to take a tire that had particularly good test results with respect to slip (and other factors) you could vastly change it's caracteristics by stretching the side wall slightly .....That is not to say the end result makes for a better or worse handling situation ,it will however change how the tire responds to heat,slip,road surface etc......And that was why we did it, because it offered us a way to manipulate handling charateristics cheaply. So all that relavent tech aside you can still completely change how any tire responds under certain cercumstances by how ,or what ,rim it is placed on...
To much the same thinking these thought lines are used all the time when manipulating tire pressure itself....change the pressure = change of characteristics...simple really. Only real thing that matters with tire stretching as it relates to modern day cars and equipment is that it is simply not nesessary....I can get better results by adjusting a sway bar or dialing in a set of coilovers....options that were only available to a very select few when stetching was used as a "tool"...
I guess the point I am trying to make is to not "overthink" what stretching was about then and now....then = usefull....now = suido bling...