I had Tourances on my tiger 800 worst tyres I have ever used pulled them off after 5 rides. Would not have thought 3 or 4 psi ether way would cause the front to wobble. Low psi makes it hard to turn as you will know. But at 25 to 30 mph 1 or 2 psi would not cause the wobble. This may sound silly but check the head stock nut is done up right. I had one come lose some years back on a hornet 600. that made that wobble, half a turn and it was sorted. Probably not that but worth checking. As if bearings are not greased right it could loosen the nut a bit when bars have been turned. Just a thought