while the ET number will give an indication, it really depends on the alloy design.
If you find an alloy that fits with a specific ET it does not mean all alloys with the same ET will fit over the brembos.
Therefore the only way to be sure is to put one on the car
if you can find a decent helpful
shop you could ask nicely if you can pop one on to see whats required. They dont need to put the tyre on initially to see if it clears the brembos, if they do then great.
If you need to start putting spacers on then you really need the tyre on to see if they protrude from the arches. (MOT fail).