Offset question

[Adrian E]

Quick query, which I think I know the answer to but would like confirmation from someone else!

Been offered a set of winter wheels and tyres, but the rims are off a B5 RS4. The offset is ET20, which I THINK means they will stick out an extra 25mm each side compared to my ET45 20s? Can anyone confirm I've got that the right way round, or if it might be feasible to fit them?

I know I could try them on the car to check, but they're half way up country and don't know anyone with an early RS4 down here to borrow a wheel off to check!

Conan suggested to me that ET35-45 would be fine, so suspect these will be too much.....

Adrian