So today was my very first sub-freezing commute to work. Not by much; it was 31 out during the majority of the ride. When I was riding I noticed the shoulders of the road had frost on them. It didn't look like ice, but I'm wary of black ice. It didn't seem to affect my traction on the ride this morning so I made it to work just fine, no slipping or anything.

But this got me thinking. At what point will riding on my current tires become dangerous? I've got Schwalbe Marathon Plus's, which Schwalbe rates as "Below average" for winter grip.

I've been thinking of going for studded tires lately, but I have no idea if it's an investment I want to make. I am probably going to end up retiring the bicycle as soon as there's enough snow on the ground to go skiing on regularly (won't be able to commute to work after December 1st anyhow, office is shutting down, so my commuting career is ending). I think my body has decided it doesn't want to lose any weight from cycling anymore, so it will be nice to switch things up with a new activity.

Regardless, I plan to keep on cycling until December 1st, and I have no idea how to tell whether riding will be dangerous or not. Any advice would be purely awesome.

Thanks!