i have dunlop direzza'a on my SI wheels, and they are really loud, like a humming, when im driving. It is much more pronounced at higher speeds. but when i turn left, or go around a left curve it goes away!

Could this be fixed by an alignment?

Or what could it be?

 

Are you talking about the supersticky Dunlop Direzza Sport Z1 tire, or the budget summer Dunlop Direzza DZ101 tire?

Have you checked the air pressure in your tires and set them to the recommendation for your car, in the owner's manual or on the door jamb?

Is the car pulling to one side or the other?

Have you checked the treadwear on your tires and have you noticed any unusual wear patterns?

These are all questions whose answers can help determine the source of the noise and/or the need for an alignment.

 

What kind of road temperatures are you running on? It might be that the summer tire gets harder in the cold and thus louder. Just a guess.