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Your tire/wheel combos act as giant gyroscopes when you get them rotating. There are some complex force vectors created. As the diameter/mass/moment of inertia increase - for instance changing to bigger tires - the force levels increase also. At some point the internal damping (read friction) in the steering system can no longer dampen out the those forces. That is where the steering damper comes in - and that is why you see them on trucks with big wheel/tire combos and not Luminas or even 1/2-tons. The damper will keep the shimmy out of your steering wheel. If money is tight, try driving your new tires without the damp, then add it if you need it.
The larger tires increase breaking distance because you are increasing the lever arm. With stock tires, the braking force occurs roughly at the midpoint of the brake pad or at the inner drum diameter - somewhere around 6 inches from the axle centerpoint. The force of the vehicles mass fighting against the brakes occurs at the tire/road interface. The "rolling radius" of a 28" tire is roughly 1 inch less then the standard radius - so 13 inches. The ratio of your lever arms are then 6 to 13.
Put on the 33s and your rolling radius becomes 15.5 inches. Now your ratio is 6 to 15.5.
-dch
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