[s-cars] Stopping - Tire patch questions

[Kirby Smith]

One should not assume that tires behave as classical friction surfaces,
except when already sliding.  Else, fuel drag cars could not meet their
demonstrated accelerations.  Tires act more like cogs until breakaway.
The goal of a performance tire design is to extend the conditions over
which the cogging applies.  Wide tires of low profile provide better
side cogging stability.  I suspect, although it is moot for passenger
car tires, that a large diameter tire would be best for longitudinal
braking.  It is certainly the case for acceleration in dragsters.

kirby


Richard Tanimura wrote:
>
> Linus wrote ..
>
> My understanding is that best acceleration (negative accel=braking) is with
> the
> tire just slipping...about 5% or so.  Keeping a tire on that threshhold is
> the
> key, and (generically speaking) the reason to install better brakes on a
> street
> car even for the one stop situation--better brakes in this context meaning
> brakes that give you better feel and modulation of braking pressure than you
> get from stock brakes, so you can hold that pressure point.  Yes, the Big
> Reds
> definitely improve that feel over stock.
>
> ....
>
> Your understanding is quite the same as mine. The simple reason is that the
> coefficient of rolling friction is higher than the coefficient of sliding
> friction IIR high school physics correctly. Just below the threshold of that
> transition is the optimal point.
>
> I don't know if I follow you on the modulation. On my car w/o anti-locking
> brakes modulation is important. But on my S2 with anti-locking brakes on the
> car I don't understand the need. You can stomp on the brakes as hard as you
> want and the electronics do the modulation for you i.e. keep you at or near
> the threshold. Or am I missing something as usual?
>
> Rich
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