Square lips, beefy contact, and a whole lot of roll speed.
The main things to think about when it comes to a race wheel is contact patch and diameter.
Diameter is how tall the wheel is, and mainly comes into play with the amount of roll speed you will carry, or how fast you accelerate. Do you want to keep a lot of speed in the flats? Or do you want to be the fastest accelerating? Race wheels generally come in sizes like 70mm, 72mm, 73mm, 74mm, 75mm, 76mm, and also all the way up to 80mm. When picking the wheel size, keep in mind the clearance you have on your board and if you want to have to run riser pads.
The contact patch is another thing that will determine how much you grip. This is how much of the wheel is actually touching the pavement, and plays a big role in if your wheel will break loose or not. Bigger contact patch wheels are always a great choice like the Waterloo Rallies, but a smaller contact patch like the These KRF Stage 1 72mm will also be another good choice.
When it comes down to it, you start to develop a certain relationshop towards and brand and generally stick to what you know works best for you.