what offset do i need if lowering my car 90mm??

[Adz]

Ive got a 2004 1.2 clio and im going to coilovers on it and drop it 90mm all round what offset do i need is it ET40 ?

 

[will.clio!]

I have a set of ssw nirvana wheels, 17x7'' ET42, and lowered 90 at the back, had trouble with the arch scrubbing, but folded the lip up and it's okay now.

Not a great pic, but you get the idea.