For the last several weeks I've been noticing more and more course black sandy like stuff covering my bike, lower legs, and bags after each ride to and from work. It's definitely thicker after a rain and it's hell on my brakes. I have to wonder if this is a by product of all of the studded tires on the road lately in the Vancouver/Portland area. Any ideas?

Not the studs but the calcium chloride they put on the roads makes this sticky brownish gunk that hardens and leaves a residue.

Its a dirty world.. they spread gravel on the Icy well used roads after a freeze. [salt not used here]

Portland gets colder than the Coast in the winter..
big cold airmass behind the Cascades comes down the Gorge.


studded tires do chip away at the road surface. I5 has double track grooves.

one spot in the bridge west of here the concrete road bed
is chipped down to the steel reinforcing wire grid.

volcanic ash. had any eruptions in the last week?

No eruptions lately. There also hasn't been any sand and gravel dumped this year for the ice (yet). Lots of spraying lately but this stuff is like a course sand and there wasn't any of this amount a month ago or so which is why I think it might be from the roads getting chewed up from studded tires.

Even in summer tires wear on the road surface.. road wears the tires, its a mutual consumption deal.

Could be, but my money is it's just the usual winter dirt/salt mixture.