I’m not an engineer and I don’t play one on TV. But this is what I’ve culled from years of reading about the subject of uneven tire wear. And if I’m full of bull, one of our resident smarter people (of which we’re blessed with many) will tell me so. Gently, please.
Your 4 degree relative difference in lean angle breaks down with superelevated road surfaces. Most
horizontal curves with design speeds that result in lean angles of 30 degrees should
be superelevated. Maximum superelevation is generally about 8% and is consistent across both lanes once through the transition. The transition from normal crown to superelevation varies, but generally half to 2/3rds of the transition happens prior to the point of curvature and thus the slope differential across the two lanes is gone prior to entering the corner.
Federally funded roads to include most state routes should be following the AASHTO guidelines regarding superelevation. Local and county roads are certainly less consistent.