For maximum performance and control, the rear end of a slot car must break loose and "drift out" a little in the corners. This "power on" slide enables you to take the corners much faster than if the car just tracks following the slot.

THE "LOOSE" CAR - NOT ENOUGH TRACTION
If the rear tires don't provide enough grip, the rear of the car will slide out too easily, or it may "fishtail" making it very difficult to control the car. The car will slide out until it can go no further because the guide flag is locked all the way to one side. At this point the car leaves the slot. This de-slot is the result of having not enough grip or traction.

THE "TIPPY" CAR - TO MUCH TRACTION
A slot car can indeed have to much traction. When this happens the rear end of the car cannot "break loose" and slide out in a controlled power slide. The rear tires track tightly following the slot. But if the car is driven too fast, the car will suddenly tilt and the guide flag tips out of the slot. When a car is tilting out of the slot it usually will head straight into the wall. This happens very suddenly and makes it very difficult to race the car without de-slotting.

BOUNCY, BOUNCY
Another way a slot car can de-slot is when it is bouncing or chattering on the rear tires. This chattering can sometimes become so severe that the car actually bounces out of the slot. The chattering is very undesirable. It is usually caused by a broken chassis or motor mount, a bent wheel or axle, or worn out bushings.


THE HAPPY CAR
When the car is set up properly, it will drift out into a controlled power slide. If you drive improperly, it may tilt out of the slot or it may slide out. It won't always de-slot in the same way. It will be much easier to drive and race than a car which always slides out or always tilts. By observing just how your car is de-slotting when you race it, you can tune it by changing things to make it run better.....


If the car swings out to easily.....
Try grippier or wider tires.

If the car tilts to easily....
Try firmer tires or narrow the width of the tires.

Try adding lead weight up front.

Are you using the proper size of tire? Tires that provide the minimum legal clearance will work best. Taller tires make the car tippy.

I think your post describes traction tuning very well Observing how the car handles and how it deslots is very important to get a fast car that is easy to control.
I would like to mention that you can also change the handeling without changing tires. When the tires are fixed, similar tuning can be made by moving the weight in the car. For more traction, more weight is added in the rear. For less traction, more front weight.
Traction will normaly get better during a race, so tuning for a low traction track can be bad and slow things down when running a long race.