Wheels are front
18 x 8

Wheels rear
18 x 9

ET: 40MM
5 x 120

Spacers needed and if yes, what size?

These wheels are off e46M3

Good lord. Spend the time figuring out what offset means, and how to use it, and you will never need to ask another question like this.....

As for the answer. I'd say 18mm-20mm spacers will do you fine. That will give you an offset of 20-22, which should ok.

Will

Sometimes, you just need to hear it from someone else for re-assurances...thanks

No worries. On big money rims like the LM's, I can certainly understand why.

Will