Before I get down to my question, I'll provide a little background. I
recently had to drop my Mechanical Engineering degree because of the way
my school was handling me (LONG story). Anyways I have an extra five or
so hours per night when I would have been doing calculus homework. So
with all this free time I have been working on setting my V8 up to be a
better autocross car. (Read: I have been applying way to much math to
suspension design and upgrades, to keep myself busy-er)
Now for the car content. I have been working on a formula to calculate
tire size needed for a given amount of power. What I am trying to do is
figure out how much rubber to I really need to have on the ground given a
set of performance data. What I am down to now is I have a coefficient of
friction of a set of tires but can't relate that to a tire size. What I
have is 500lbs on a tire with coefficient of friction of .8 so 400lbs of
traction force (round numbers chosen and ignoring weight transfer etc for
simplicity). So I have this but I don't have a tire size. Obviously if I
put bicycle tires on the car they would loose traction, but if I put drag
tires on they wouldn't even though both might have Cof of .8
So how do I relate Cof to traction force and to tire contact patch area?
If anyone has some insight, maybe not a solution I would be interested to
hear it. Also if such a formula for calculating tire size exists I would
like to see it. Many would suggest just go to bigger tires, but since car
is for autocrossing low unsprung weight is important. Also big tires =
big $$$. I don't want to make the car look too fast for insurance reasons
(I'm only 21) but I don't want to pay in handling/acceleration because the
tires are too narrow. So I want to actually derive the tire size that I
need. Anyone know more about this stuff than me? I'll be glad to share
formula with everyone, but I have to figure it out first.
James Nazarian
'71 B roadster
'71 BGT rust free and burnt orange
'74 BGT going by-by soon
'63 Buick 215
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