Several of us have seen the same wear pattern. I asked the same question a couple years ago and there was no real answer.
https://www.montanaowners.com/forums...ad.php?t=85520
I still have roll-off on both inside and outside edges, but there is a lot of tread left. I finally decided to just run them since they will hit their five year mark next summer and will be replaced.
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Scott & Alta
2017 Montana 3160RL, Legacy, Onan 5.5Kw, Solar
2022 F-450 Lariat Ultimate