Mk3 golf spacers

[LEGGIE]

Hi All,
Im leggie and im new here, so hello,
I've got a 1995 golf gti colour concept in black,
After relizing i've not payed enough road tax, i manage to hit a pot hole and split one of my rims 
The rims i've got at the moment are rs4 5x100 et42 17x7.5 with 205/40/17 boots
The rims i've just ordered are 17x8 et40 5x100,
What i would like to know is, Do i need spacer's to fit these rims on my golf, (i know, i know i should of though about it before i hit the order button lol)
If i do, what size spacers do i need and which ones do people recomened, and where from.
Thanks in advance for any advice,
cheers

[R98 HUF]

i think tyey'll go straight on.... mine were 35 and went on........

[boneybradley]

they will sit further out in the arch not further in so will fit without spacers....

[gribsymk3]

Am i right in saying the bigger the offset the further they sit out in the arches?? an et 42 would stick out more than an et 35??

[Len]

I believe that to be correct.

[zorro]

Am i right in saying the bigger the offset the further they sit out in the arches?? an et 42 would stick out more than an et 35??

Other way around is it not? Small or even a negative offset means the rim sticks out further...

[mattneck(Beavis)]

Am i right in saying the bigger the offset the further they sit out in the arches?? an et 42 would stick out more than an et 35??

Other way around is it not? Small or even a negative offset means the rim sticks out further...

it is indeed the other way.. the lower the offset the further from the hub it is.. and closer to the arch 

[boneybradley]

 the lower the ET/offset the further away from the brakes they are

....so I was wrong and the last posts were 100% having a et35 offset and using 3mm spacers gives an offset of et32!!

[Len]

OH I'm confused!!!!

I have scooby wheels with and offset of 15! To fit my car I had to have 20mm spacers.
Work that out and explain it to me please!

[Mew]

So you have an offset of -5 Len?