ok, looks like not alot of people gave you the help you needed, so looks like i'll help you out.

basically, there are two types of drift tires that are widely used: abs and pvc
pvc is very popular, but in my opinion, pvc is too slippery. also, it is white, which tends to be somewhat of an eyesore
abs on the otherhand is a differnt compound and in my experiences works better. it is also black, so it looks scale.

you can obtain both of them at any hardware supply store, i got mine from orchard hardware. and the good thing, its CHEAP! about 25 cents per foot. as for size, you want to get 2 in piping. you can ask the person at the store to cut it for you (bring a sample wheel to test the size), or you can do what i do and cut it yourself. i used an x-acto model saw as opposed to a chop saw or a bandsaw, because its more precise (and cheaper) and it doens't shred the material up. to get rid of any imperfections that are inherent with handsaw work, i trued them on my lathe and then balanced the mounted tires and wheels.

now probably the biggest problem most people encounter is mounting the abs on the wheel, as the abs piping was never really made specifically for rc wheels. there are two types of touring wheels out there. i believe yokomo first introduced the concept of "inch up" wheels. a standard wheel is 2 inches, but an "inch up wheel" is 2.1 inches. many wheels now have the 2.1 size, which will not fit in the abs pipe. you can either take some material off, or just start with 2 inch wheels to save yourself the trouble. some people have even had the wheel being too small, bu this is an easier problem to fix. just wrap some electrical tape around the inner ribs on the wheel and slide the abs on the wheel with a friction fit

here is a picture of my abs wheels

hope this info helps you
happy drifting!