There never seems to be much discussion on reducing the harm from tire (and I suppose road surface) particulates. Maybe that's the next frontier?

There's quite a bit of materials science work in that direction.

For example, I have Michelin's CrossClimate tires, which are all-weather tires that do better in snow but don't break down as fast as dedicated winter tires do in warm weather.

How would you recommend them based on winter performance?

I live in a snowy area and am quite happy with them.

I believe they are directional tires so it would make it hard to operate with a full size spare otherwise I’ll definitely consider them

I was thinking more from the perspective "make them out of materials that aren't too bad to inhale/ingest"

Sure, that's great too. But the rubber lasting longer means less of those bad things to inhale floating around at any given time.

What material is strong, malleable, dirt fucking cheap, has a high coefficient of friction, easy to work with, amenable to additives, meets all the suspension properties we expect out of a tire, etc, and isn't bad to breathe a lot of the dust of?

Modern tires are works of material science miracle, working with dirt cheap inputs.

Even iron dust from steel on steel friction like with trains is bad for your health.

The human lungs just have bad filtration.

If nobody asks the question, nobody will try and look for one.

Because a hard long wearing tire is a low grip tire and the direct tradeoff between safety and the environment is not something either crowd wants to deal with because there's so much overlap.

EU is introducing particulate regulation roughly now-ish (proposed 2022):

https://single-market-economy.ec.europa.eu/sectors/automotiv...

> Euro 7 will also regulate emissions from tyres and brakes for the first time worldwide.