Any time I get above 55 mph my car will vibrate and I can't tell tell if its tire balance, or suspension components. I have 2 new Yokohama YK520s in the front and the rear tires are older pirelli tires and I'm not sure if the rears have been balanced recently. I had new lower ball joints replaced recently under warranty and new tie rods. The steering wheel does not vibrate at all its just the whole car in general and it does it at 55mph and 75mph the most, but even cruising at 65 it will do it a bit.

 

I would check the wheel bolts first. Most likely they need tighten

 

and if that checks out, take your car to a tire place and see if they are balanced correctly.

since you said it wasn't in the steering wheel, it most likely means its the rear tires that are causing this, and since those are the older ones, it makes sense

 

balance, misalignment, bent rim.

 

balance and bent rim...yes

misalignment...no

 

i've been hearing that if you're car is out of alignment, a slight vibration can occur at higher speeds. Low tire pressure may also be the case but I highly doubt it.

 

someone told me that too, but auditech corrected me

 

tire pressure is all good, it rode much smoother with the 18s on it then it does with these 17s so I'm thinking loose wheel bolt or bent wheel. Thanks for the info guys