No, it isn't. It is a mere 5mm per side in regard to width.Judging from the carnage your fenders don't appear to be rolled enough. Those fine cuts at the top and gashes on the sidewall tell the whole story. I'd reroll them. Even my 305-35-18s on an 18x10 will rub that driver's fender under certain conditions, but it never cuts into the tire. Only a light scuff on the top of the shoulder which goes away with a bit more driving. Would hate to see you eat another nice tire thinking the difference between a 315 and 305 is that significant. It's really not (imo).
You are lower than I am, but doesn't look to crazy. As long as you don't have sausage fingers how tight is the gap(2 fingers, 3 fingers) I have a little over 2.5" of clearance from the fender to top of my tire. I may close this by half an inch.
I have been keeping it wider due to running 28" slicks for the track, but never go anymore so I can close it a bit.
Maybe since you have coilovers just open the gap a bit and see if the issue stops?