Is a -1.8 rear camber bad

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. -1.0 degrees is the specification - -1.8 degrees is definitely too much. However, camber is not a tire wearing angle, generally. I would say do it as soon as possible, but I would not consider that specification (without knowing anything else about your vehicle) a safety issue. You can always get a second opinion - https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.