where exactly are you rubbing on the fender liner? I'm wondering if it's because of the 305. I know there a ton of guys running much more drop that don't seem to be having the problem, but they all run 22s and narrow rubber band tires. If you follow "ram_trucking" or "ramloyalty" on IG you will see a ton of guys with slammed static drops.
Could you mod the liner at all? When I had my 2010 F150 I had 4.5/6.5 drop with 305/40r22 and I had to heat up the liner with a heat gun, push it back with the head of a big dead blow hammer, and hold it there until it cooled down. I basically just remolded that spot of the liner where I was rubbing so it would clear and I never had any more problems. Just a thought.