Insane speed in german cars... [Maxima] (+ tire slip and stuff)

[amalventano@sc.rr.com (Allyn)]

> i.e the slowdown when the tire first contacts the
> road is cancelled 100% by the speedup when the tread separates from the
> pavement?
>
> Follow me?
>

yes, this does happen (or else the tire would tear into 2 pieces), though the
'damage' is already done. the only part that matters as far as pushing the car
is the contact patch area. since the slow-down occurs there, this ultimately
results in the rim rotation speed going faster than normal for a respective road
speed.

if there was a way to apply an outside force to a rocco such that it was 'stuck'
at 100 mph, your speedo would show 100 mph while coasting, but would read
slightly higher than 100 at full throttle. likewise, it would read slightly
lower than 100 while braking (assuming you dont lock the wheels).

another important thing to realize is that tires do this laterally as well
(turning). instead of just slip, its called 'slip angle'. when you try to turn,
your tires are pointed at a sharper angle than the front end of the car is
actually going. as tread blocks come in contact with and grip the road, they
begin taking some of the sideways load, causing the sidewall to shift over in
that section. this sidewall shift gets worse until the tread section reaches the
rear part of the contact patch. it then rolls away from the road, lets go, and
the tread section then returns to its normal place.

you might think you could turn the hardest with no slip angle at all, but most
tires generate the greatest lateral grip while slipping at a 5-10 degree angle.

i'll bring my bosch handbook back from work tomorrow and try to scan some of the
tire charts. they show it pretty well.
Al