[///MPhatic]

Does anyone know how to calculate increased outside fitment room as negative camber increases? For example, if I wanted 8mm more room to fit wider tires, how much negative camber does that equate to?

[Carrera2RS]

If you're talking about outside wheel clearance to the arch and using top mounts to adjust camber that's something like 1 degree or less of camber. If you want to be accurate measure the top of the tyre edge to the height of the shock mount to the hub so you can see where things will move from when the top mount is moved and use Pythagoras

You are trying to see where the wheel pivots from as it will give more clearance than just rotating about the hub. If the wheel just moved at the hub centre 1 degree would move the edge of the tyre in by around 5mm for example