Thanks @lisadim,
So these are the common 805R/341F primers which give an estimated ~464 bp amplicons size which on a 2x300 cycle run should have just about ~140 bp overlap. For proper merging of paired reads following denoising we need a minimum of 20 bp overlap + some wiggle room for natural size variation of this region. Basically we want to remove as much of the poor quality reads as we can up to ~110bp.
Based your quality plots I'd say a good starting point would be to truncate your Forward reads at the ~260-270 position and your Reverse reads at the ~240 position. In addition you should trim about 25-30bp from the 3 5' of your Forward reads to get rid of that initial dip that may lead to discarding of some reads.
Let us know if you run into any issues.