Yes just put it on the scales and move weight..
dont just add pre load.. that will just make you
turn left on the shut down.. then see what you
have... hopefully it will be level

So what size anti roll bar? Is it one size fits all for the diameter?

NO! The effect of an ARB varies as the 4th power of the diameter: a 1" bar is over three times as stiff as a 3/4" bar.
This will also vary greatly by the length of the link (or arm) to the chassis: longer softens bar action.
If you're adapting an existing bar, one with splined ends makes pre-load bias easy.

If it has chassis flex, no amount of adjustment is going to keep it from rolling over.

As for the tires....MORE air is going to wrinkle the tire HARDER as it puts more rubber on the ground and INCREASES bite. Looks like it has more than enough bite now........too much