Traction: Think of it this way. Your tires have a number of points, based on the tires, of traction to spend every click of the processor clock. The game doesn't use this points system (I think), but it is a solid way to look at it. You can spend these traction points on 3 things:
Accelleration -- Speeding up.
Decelleration -- Slowing down.
Turning -- Changing direction.
Let's say super-soft's have 100 points of traction. If you're acellerating full-bore in 4th gear, just over the redline, you're using, say, 90 points of traction. You come to a turn, and you have 10 points to spend in turning. I hope it's a shallow curve!!
Now a n00b, like me, will crank the wheel into the direction of the turn and try to spend 100 points of traction on turning. However, he's already spending 90 points in acelleration... so he creates 90 points of slippage on the tires (slippage is traction defecit). He goes careening into the wall.
After being schooled by his buddies at work, the n00b comes back. He says, "By golly I need to slow down!" So he lets go of the gas and crams the wheel to the right. 100 points of turning still, but coasting only dropped him to spending 85 points of traction. SCREEEEBOOM 85 points of slippage! So he decides to read the manual, but doesn't "get it" and says, "Oh! I need to brake in turns!"
So Mr. n00b screams down in high 4th, slams the brakes just before the turn, a moment later jerks the wheel to the right and keeps braking. He's spending 100 points on braking, then--still spending 100 points on braking, spends another 100 points on turning, so creating a 100 point slippage defecit. SCREEEEBOOM.
Mr. n00b finally gets schooled by his girlfriend, who can also drink him under the table BTW. So he starts braking at the 50m marker with his thumb hard on the button. Gently, in a feminine manner he trades pressure on the brake button for pressure on the analog stick, trying to turn the stick only as much as he's eased off. Magically, he takes the turn beautifully--at some processor ticks, he creates 2, 5, maybe 10 points of slippage. Some ticks he still has 2, 5, 7 points of traction he could have spent. But he's learned to turn.