car shakes at 90ish KMPH

[ckh]

Mine's going to the mechanics soon, to finish off a few things - including that wobble.

I'm lost as to why my truck, with skinny tyres, does it too. I even swapped my 2 brand new, balanced spares and put them on the front.

All things aside, I really, honestly believe, with all my heart, that it the wobble is partly due to the condition of the road. I live in the wheatbelt where b doubles and road trains are a part of daily life.
The heat our here melts the bitumen, too. I'm reasonably confident to say that my skinny tyres get caught in the 'invisible' truck ruts on the bitumen.

99% of the wobbles happen when I'm braking.

Mine's not the only vehicle that way that has gone to the mechanic for the wobbles.

Rossco

If 99% of your wobbles happen when braking could it be a warped or stuffed disc rotor?