Thanks for the inputs.

DD, the front tires are new (changed it abt 2 days ago)..but however, the problem still existed before i changed them. So, i would rule out its the front tire defect.
Secondly, the camber for both front tires are at -1 on both sides. I'll check for toe and castor settings later today.

nick_m, i dont think its bump steering since its happening at the rear. I faced bump steering issues long time ago, and changing the idler arm solved it.

Based on all your inputs, im suspecting it could be the rear toe. This part normally would be neglected since the setting could not be adjusted. By the way, any tips to get the rear adjusted? Im not sure on the toe, but the camber readings shows -0.5(left) & -0.6(right).

Thank you