Since I feel it necessary, I'll talk some more about tires.
In this article I will discuss tire slip, wear vs traction, tire preparation, and size/stagger.
Tires generally have more grip when they aren't spinning out. I say generally because in all honesty this isn't true all the time. In reality peak traction for most tires occurs at about 10% slip, any more and the traction will drastically drop off.
This slip is in every direction, not just in drag racing. If you take a corner hard enough that you can hear the tires just start to slip and squeal then it is a very good indicator of how close to the limit you are. The same concept also applies to braking. You will stop faster if your tires are spinning slightly slower then the ground is passing. But if you hit the brakes any harder then you risk locking your brakes up, sliding tires have little traction. If you do start sliding, you either have to wait till you skid to a stop or the speed you want, or waste time by letting off and reapplying.
Wear and traction are closely linked. The harder you push your tires the more they will wear. The more they wear the less traction they will have. Kinda... again this isn't entirely true, brand new slicks will work best after they have had a few laps put on them.
Keeping in mind that tires work best after they have been "broken in", most race teams will scrub a set of tires before the race. Scrubbing doesn't mean they get out a bucket of soap and water and clean them... scrubbing is the act of putting the car out on the track, running a couple really hard laps to get the tires up to temperature, then running a couple soft laps to let them cool down and get in their optimum state.
Other things to keep in mind with tires is that with soft racing tires it is very easy to mark up and dent the surface. Leaving the race tires on the car isn't a good idea. Putting on some spares during transport and storage is often the best course of action. And always avoid running over scraps of metal!
There is such thing as tire softening compounds, these chemicals break up the outer surface of the tire causing them to have more traction and warm up faster. In most racing leagues they are illegal, so I advise against using them. If you do use them... put the stickers back on the tires to cover up your evil treachery...
Finally, size and stagger.
Tires vary drastically in size and characteristics, optimum tire choice and placement can mean a lot in the overall performance of a car. Typically for road/track cars, keeping the tire size equal on either sides of the car is desirable... this of course depends on the size of the course, if on a really small track there may be only one turn in the opposite direction.
Stagger, is the offsetting of tire sizes so that the larger wheels run the outside of the corner. If it makes corners easier to drive and limits the amount of work that the differential needs to do. For oval track race cars, to not use stagger would be just plain ignorant.
On a final note, it is possible to change tire size by as much as a couple inches in circumference. All you need to do is pressure the tire well past it's stock pressure and let it sit in the sun for a few hours. Hopefully rotating it so that one side of the tire doesn't grow more then the other ;)
Hmmm... next time, I'll change it up a bit, save spring rates and sway bars for another time, and do an introduction to some sort of engine stuff... probably resonance or control systems.