Recently my 1994 660 kancil has this problem in the morning.

There will be vibration coming from below like the front tires are over inflated. Check at service center both drive shaft is ok. I have also change the steering rack and calipers for both front wheels which were making squeaking sound before that. The vibration happens only in the early morning in the afternoon the vibration is not noticeable.

Any suggestion what could be the cause?

Yes I had my tires changed about 2 months ago.