For what it's worth, I'm also learning the M2 after coming from a mid-engine. I initially found myself over driving the front tires, partially because the M2 is so good at managing mid-corner attitude adjustments and fun to drive. Once I reigned in the enthusiasm and got back to managing weight transfer (like I was still driving a car with only 48% weight on the front wheels), lap times dropped and shoulder wear slowed down.
From the looks of those Cup 2's, I'd guess they're getting more slip angle and heat than they like. My RE-71R have 2x the sessions (usually with a passenger/student for even more weight) driving it for personal best lap times, and still have another day in them. I ended up putting in camber plates, but haven't driven with them yet.
I'm step out and say you might just be doing the right thing by looking to tighten the nut behind the wheel first. Yes, even instructors need to do it...because we're mostly still amateurs too!
