Hoosier Bias Ply - Negative Camber?

["Mike Keyes" <mnkeyes@sympatico.ca>]

Hello!
I am trying to discover whether the Hoosier Bias Ply Autocrosser 
tires require less camber than the Hoosier Radials. I have read that 
the Bias Ply require only 1 - 1.5 degrees of negative camber, is this 
correct? (225-45 13  Hoosiers on a 1990 Miata). Why would the 
Bias Ply require less negative camber than the Radial?

Thanks.