Well, a pyrometer is the best way to do it, but for a beginner, shoe polish is cheap and enough of a no-brainer to use that its okay to use. Not optimal, but good enough to get started with. Especially if you don't have someone explaining to you what it all means, and what adjustments need to be made. Also, you dont' have to be in a big rush to check the tire temps right after a run, and you can go around and make individual adjustments at a slow pace. I used to make shoe polish marks on the insides of my front tires as well (with my old RWD solid axle auto-x car,) to see if caster needed adjustment. I'm currently prepping an Accord for FSP, so thats a whole new world, but its geting there.