Tires: Mixing different brand tires, emergency maneuver, brand tires

Question
I have a 2004 bmw 530i. I have to replace its rear tires. The front tires are relatively new (1.5 yrs old around 20k miles on them). Right now all tires are OEM from Continental (grand touring) with a speed rating of 94V. I'm planning to put Michelin's (ultra high performance) on the rear with a speed rating of 94W. Is this a good idea or will it pose problems later on. I appreciate you response. Thanks!

Answer
Ron,

The general rule is that all 4 tires should be exactly the same, including the wear.  That's why regular rotation is important.  Unfortunately, BMW has placed an emphasis on handling and not tire wear, so they don't recommend tire rotation - and they are as wrong as they can be.

But back to the general rule:  The further away you are from "exactly the same tire" the greater the risk of something bad happening - and unfortunately, that "something" is going to occur when you need the vehicle to behave - in an emergency maneuver.

In your case, Michelins handle quite differently than pretty much every other tire.  Add that to the fact that you are going to have tires with different amounts of wear .... well, that isn't good.  

I would say this is borderline - so this all boils down to how much risk you are willing to accept.