Ok sorry I remembered wrong. My wheels are ET20 so with the 3mm spacers they would be ET17. Anyway 18x11 ET24 would have about 5mm more clearance to the lower arm than mine. Which coilovers do you have?
I took a couple of photos of the clearance to the lower arm. Clearance to the coilover is about the same. (HSD HR)
lowerarm_clearance1.jpg
lowerarm_clearance.jpg
If you want to drive fast get the higher et rims, but if you want to go for the all show no go direction go ahead and fit the low et rims to stock arches.