Alignment can be off without tire wear issues, but if it ain't broke don't fix it . I'm at 12.5k miles now. My front tires are wearing close to 2/32. Probably by 17-20k miles they will drop below 6/632 (8/32 new), then Iwill rotate them until the now fronts (old rears) get down to 6/32. I think 60k might be possible on the set, maybe more if they don't get a noisy wear pattern.
You did check it, if your tire wear matches mine you are golden. If they're gone in 20k you have a problem.
regards
mech
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View my fuel log 2015 Mirage de 1.2 manual: 55.7 mpg (US) ... 23.7 km/L ... 4.2 L/100 km ... 66.9 mpg (Imp)