would need more info than that. what size are they, plus that offset is very low so might need big spacers to avoid the rear beam
I've got et45 wheels on a mk2 with brembos and 280mm discs. with 10mm spacers on front the callipers are very close to the spokes, rears are fine on brakes but as beetie says, watch out for other clashes such as beam or shocks. might also look silly without spacers.
i had et 40 wellers 7x15 on mine, loans of caliper clearance but the tyres polished the paint on the ARB, so check for that
The design of the wheel will dictate brake clearance, with an offset that high I'd be worried about it catching the suspension. I have 6.5x15 et41 Compos on my Mk2, used to run them without spacers and 195/45 tyres and there was probably 1-2mm clearance on the rear beam. When I went to 195/50 R888s I fitted spacers as I knew they would catch on the suspension.
http://www.alloywheelsinternational.com/wheelfitmentguide.html this site has some good info on it for center bore size, offset and PCD. I run ET45 on my mk2 with 10mm spacers to clear my suspension
According to that New Mini offsets are et35. I'm going to assume that the wheels are 6x15 et45, and you are looking at banding them to 7"? If that's the case, then the et will change as well. The offset is how far either side the mounting face is past the middle, ie, if a 6" wide wheel had an offset of et0, the mounting face will be smack bang in the middle. When you band wheels or fit deeper dishes, it not only makes the wheel wider but effectively reduces the offset. If I got my calculations right it will go to et32ish. In which case, you should be fine.
Riley put mini wheels on his rado and needed the centres bored out a little. edit: just found the post -http://clubgti.com/forum/showpost.php?p=1527083&postcount=63 also et48
the wheels i looked at were 5'5 wide so I was going to add 1 inch for the front and 1.5 for the back!
Yeah you can band either the outer rim to give extra dish and a lower offset, or band the inner rim which will retain the original amount of dish and make it a higher offset. If you get the inner rim banded then that will give offsets of et64 and et70.