Swift is right about that, don't mix tires, I've taken a look at the 'who cares about sim tires?' thread and a lot said there is more or less what I had figured when I first started drifting, mixing tires can and will destroy the balance of a car. It might be good initially for beginners, but that kinda really would be one of those things to real life only (I mean in the begining, later you would have to master drifting with all 4 tires having equal grip). It's just me but that's how I look at it and many others. Why? Mixing tires will hold you back, you just nead to learn how to break the traction of all 4 tires without 2 of those tires already having far less grip than your fronts. I dunno what others would suggest for settings on the rear, I'd buy a LSD full customize for FR and have the initial torque/acceleration/decell set between 40-60, you'll learn throttle and steering control preaty fast, espically with high power cars and it woun't be long untill you're going thru four wheel drifts approaching if not over 60mph al la initial D nearly hitting the wall (!) (and yes I've done that MANY times without ever hitting the wall, it took a long time though...).
A lot of cars you don't have to go all out for modifcations, some are driftable stock such as the S13-15, cars like the Corvette Z06 can also be driftable stock due to their power, even for the Z06's weight, it's a lightweight in the class it's in (the same leauge as say a Ferrari 360 or even F40, Nissan R34 (GT-R), Porsche 911 (996) turbo, Lan Evo's etc...) and given it's tendeny to oversteer easily, you'll learn a lot from it. In the later run though, you will want to learn how to tune your car to what you like, it took me a while before I could get a lot of my carsetups to what I actually use for races(!) to get used to sending a car as sideways as I can while mainting speed. Just keep at it, your efforts will pay off sooner or later.
That's another 2 cents from me, till later.