The minimum depth where I live is 1.6mm, so it's not a legal issue but with winter coming does anyone know from experience if that will be a bad idea to run these tires for another six months?
They are Kumho 175/70/13's.

 

Yep, 3mm should be fine. Although coming towards winter i wouldn't go too fast or quick turns

 

my tires were at 4mm at the begining of last winter, i got new tires a couple days later. not sure how bad your winter gets but if it's anything like mine, drive slow

 

Ok, thanks for the replies.
I guess I'll take it easy in the winter, and if I find that it is still really bad, I'll replace them then.

 

3mm isn't **** for driving in snow. Go out and get some decent winter tires and mount 'em on a set of spare rims. Trust me, you won't be sorry.
Look at it this way. Is it worth about $300 to have that extra bit of peace of mind? worn down summer tires vs nice fresh winter tires is a no brainer. Especially with the winters you guys get up there. Winter tires are the way to go.