My Lancer 2007 has steering wheel and body vibration while driving above 60 mph.
I have replaced all 4 tyres, polished the rotors, balancing & alignment but still the problem not solved. What could be the troubled part?
This could still be caused by your wheel(s) being out of balance. Two things you can do to see if it is still your issue. First, take it somewhere they can balance your tires for a higher speed. Sometimes the "normal" balance is not quite enough to get them right. If you get the tires balanced for something over 70mph, it may help your issue. Secondly, something besides your wheel/tire may be causing the issue. One (or more) of your rotors (assuming four wheel disk brakes) may be out of balance, causing the same issue as a wheel/tire out of balance. To alleviate this issue, you can do a "tire-on balancing", where they run the tires while on the vehicle to check the balance, then apply the proper weights to combat any out of balance situations.