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September 06, 2003
Paul...
There is probably a formula for this but,
I am "not knowing" in this respect.
All else being equal...
as the track and footprint widen, the wheelbase "effectively"
decreases.....
think go-kart. The car becomes shorter!
All else being equal...
as compared to the stock tire/wheel size,
as the footprint becomes greater, the vehicle weight load upon the tire
will effectively decrease....for this and other
technical reasons...all else being equal
you will feel this mostly on a wet or
contaminated surfaci.
All else being equal...
the stock suspension was built with the
stock tire/wheel combo in mind. As that
footprint becomes greater, more load will
be tranferred to the stock suspension than
previously. Thus, tire pressures should
come down a bit from stock however, tire
traction and heat/wear considerations ("squirm") may actually require an
increase (a matter of try it and see) over
stock...in which case the stock suspension
can be expected to take more of a beating. It's all compromise depending
upon conditions and priorities.
When I ran 185/60 Yoko 008R's on 5.5"
rims, I found 20F & 22R to be a good
compromise as to comfort and handling
for daily street driving...however, the
suspension had been upgraded and changed by lowering, a 5/8 front bar,
KYB
tubes, harder front springs and softer
rear ones. The wider footprint had more
of a tendency to steer the vehicle over
pavement irregularities, but this was
totally controllable. Turn in and traction
were terrific...in the dry this car handled like a go-kart. But, in the
wet, you really had to slow down (which is as it should
be anyway. for normal road driving)
With the same wheels on my BE, I run
175/70 Touring T/A's. This has stock
BE springs and ride height but, with softer
KYB GR2's (relative to original KYB's)and a 3/4 front bar. 28F & 24R
gives very
crisp handling and "neutral" understeer/
oversteer characteristics but the ride suffers a bit over the road
surfaces I
normally travel. Were it all smooth highway type surface, I'd have
stayed
with these pressures.
As it is, I've come down to 26/22....
this seems a good compromise for
excellent handling with the suspension
taking less of a beating. Turn in on this
car as compared to the former is a mite
slower, requiring more physical effort (heavy front bar)...a tendency to
understeer.
There is more directional stability as
compared to the former car. Traction
in the corners is excellent in dry weather,
not as bad in the rain as the former car.
As the footprint widens, the camber becomes more negative. The first car
('74 Midget) ran at "0" with "0" toe.
The BE runs about 1/2" neg. camber with
"0" toe.
Cap'n. Bob
'60 :{)
PilotRob@... 25041
Posted on September 6, 2003 03:24 AM
Posted to category(s) Restoration | Suspension & Steering | Wheels
