View Single Post
Old 3-11-08, 12:07   #94 (permalink)
gavin
  Total: 1558 Power: 5
 
Join Date: Jan 2001
Location: santa cruz.ca
iTrader: (1)
Quote:
Originally Posted by I4MX6 View Post
Some people like stiffer sides and others don't. I've played with slightly stretched tires and flat side tires, as well as various sidewall stiffnesses and have found that a sightly softer side allows for a better roll into a corner while keeping the tire planted and the car controlled. Too stiff a tire and it slides. But then again I don't race with r-comps...I race with soft street tires, so very different in the end.
Theres what people like and then theres whats fast.You may want to rethink your approach on tire pressures, heres why.

R-compound tires are built with very stiff sidewalls for two reasons, steering sharpness/response and to maintain the tires contact patch with the ground(which gives the tire more grip). Street tires have much softer sidewalls as they are built for comfort and road compliance but racing on them still require the same 2 characteristics of handling and grip.

For all cars, when the car is in a corner the car will tend to roll to the outside, so does the tire(even more so with a strut suspended car that doesnt have much camber gain). With low pressures the street tires wont have the resistance to stop rolling over onto their sidewalls. SIdewalls have very little grip, you need the tread of the tire in contact with the ground at all times. The solution is to increase the tire pressures to prevent the tire from rolling over in the corners. This will also have the benefit of artificially stiffening the tire(sidewalls) giving crisper steering and better feedback.

Its not uncommon to have new autocrossers arrive to events on street tires. First order of business for them...increase the tire pressures by about 8-10psi. When I was running in the Street Touring classes(street tires above 140 treadwear) I consistently ran 45+psi. This is with 500lb springs and about -3.5deg camber in front(street tires also need much more camber than r-comps...but thats another story).

Gavin
gavin is offline   Reply With Quote