When we tried 15mm spacers
we had a problem. We found the hub protrusion front and rear was greater than 15mm. we tried a set from Direnza and the hubcentric bit bottomed out before the spacer was fully down. These went back for credit.
The alternative would be to modify the hubs !!!
We did machine a set of 20mm spacers down to 17.5mm for what it was worth ! - this gained a couple of mm of arch space
You wont shred tyres or arches its just the arch liners, and this of course it all depends how low you run it and how hard you push it / brake on track.
You may find some 2015 / early 2016 pictures on here
https://www.facebook.com/DrivewayMotorsport.Project3/ , early 2016 we changed from Bilstein to KW clubsport
This is on Bilstein
https://www.facebook.com/DrivewayMo...8678907895830/926169360813446/?type=3&theater