i have the mk1 gt3 set (stocks) on my 01 996 and im getting vibration >70mph...

 

Perhaps they just need to be rebalanced.

 

Advan Sport is pretty good tire. one of few that's priced above PS2 actually. i wouldn't say it's a rough tire unless it's the old AVS Sport.

sounds like u need balance first.

 

Very pricey, I was quoted $812 out the door for a pair here in San Diego. If anyone's interested in the pair I currently have 295/35/R18, I'd be willing to make them a great deal. I'm not driving my car right now to keep the mileage on the tires to less than 100miles.

I also have the 4 OEM Turbos with Conti's on them for sale too.

 

get the wheels balanced... if it still there then you have slight bends which are repairable... but then you have to have the tires pulled the rims fixed , then the tires put on and then balance again. i think we've all been there