I have already checked the alignment and balance, and my tires still have 60% tread on them. But I am still getting some sort of vibration when I'm in 6th gear going about 75mph+ Does anyone know why this could be happening. It an 04 Enthu. Coupe; by the way. And also what is the correct method for rottating the tires on the Z (Let me guess, look in the manual, lol).

 

well if you have really checked the balance and alignment and are sure that they are within factory levels, then my next thought would be the rotors.

when was the last time your brakes were replaced? have they been inspected lately? i had an experience similar to this in my IS300, i swore it was a balance issue, until i started hearing squeaking from my brakes. turns out the rotors had become warped. it was about the same situation, vibration was bad at around 70 or 80.

another possibility is the tread. certain tires (G-force T/A KDW comes to mind) resonate at a certain speed due to the tread pattern against the road surface. many tires are louder than others. have you replaced your potenzas with different tires? stock rims and size?

 

loose lugs?

 

Could be any of the following;

-Mixed tires.
-Camber wear
-Rim not mounted properly on hub
-Broken or no hubcentric (sp?) ring
-Worn or damaged shocks (droped?, lots of miles)
-Damaged or worn CV boots

Apply any of those to what sounds most familiar.

 

do you have stock or aftermarket rims?
some cheaper aftermarket rims have a tendency to vibrate at higher speed cuz they are not well made and so are some odd off brand tires.