275s and Sluggish Steering

I recently installed some 275/35/19 PSS ON 19x9.5 ET45 wheels. They were installed at the same time as Bilstein PSS10, adj UCAs, cornerbalance, and alignment. FTG is 26" (+/- due to cornerbalance). We started with:
Camber: -2.3F / -1.8R
Toe: 0F / .05" total toe-in R
Caster: 4.5deg

After driving this setup, the steering was slow to return to center. I asked to max out caster to see if it could fix the issue. We ended up with the following:
Camber: -2.3F / -1.8R
Toe: .07deg total F / .12deg total R (I don’t know why the second sheet switched from inches to degs)
Caster: 6deg

This helped, but it’s still slow to return to center. It returns to about 1/8 turn from center, but won’t return without me correcting it. Is this due to the 275s impacting the scrub radius? Is it because of the minimal toe? I was informed we couldn’t get any more caster. Do you have any ideas what we can try, while still keeping the wide tires, or do I just need to live with it? Preferably, I’d like it to snap back to center.

Thanks in advance!