wear indicators mean nothing. many companies put them as high as 3mm, some as low as 1.6
they are not a legal requirement, and a good tool to get people to buy new tyres. pirelli for example put them at 2.5mm goodyear at 3mm
if you don't have access to a tread depth gauge, a good test is to get a 10p, if the ring of dots fall below the tread, they are still legal.