That seems most likely. I am using the same rims as you but the tires are 235 40 18, not lowered. If you like just 10mm in the back then that's great, but if you would still prefer 10mm front 15mm back then trim the plastic and roll the fender as much as you can.It's been lowered but there still seems like there should be enough gap. I think my problem is that the tires are just to big
Ya this fall I plan on buying new tires, these are almost done for, just trying to make these last as long as possible, ill try this set up for now and keep the 15 mm spacers for when i get new tires.Or run a skinnier tire like I mentioned. Its alot easier to replace tires than to uncut plastic and unroll fenders if you ever plan to sell the car. All up to you.
I just went up to 15mm in the front and 20mm spacers in the rear with 8" wide +32mm offset and don't rub but I am not running a 245 tire.