Vehicle/Tire Friction and material callbacks

I'm working on a small racing game here and I'm having some problems with the physics.

Basically what's happening is that when the car gets up to a decent speed it will spin out when you try to turn the car.

I ahve tried playing around with functyions for setting the lateral slip (setSideSlipCoefficient and setMaxSideSlipSpeed) insiode the vehicle userCallback function, but that doesn't seem to effect it.

I've been trying to set the Kinetic and static friction in my material callbacks, I did it with the car body, but that doesn't do much of anything and I can't figure out how to get the tires to have a material callback of their own.

I've looked at stuntplayground but I don't see how Walaber does it, found the section but I don't really understand his code.

I have a very similar problem, if you find any solutions please post them. I've tried increasing the static/kinetic friction between the material pairs of the car and the ground. The result was that you just had to be driving faster for it to spin (it doesn't happen nearly as often as it used to).

When your vehicle is sitting horizontal to a slope, does it slide down it unlike a normal car would? (Mine does, and I'm trying to find a way to fix that too...)