Your hypothesis then, roughly, is that braking causes more pollution when it's more extreme (since the total braking work being done is at least as great -- in practice much greater because of the increased mass), so smoother braking will reduce tire wear.

I'm inclined to believe an extreme version of that hypothesis -- I doubt 200k miles at 1mph would wear the tread substantially -- but in practice I don't think that's the case. Electric cars tend to replace tires around 10k miles sooner, so the net effect of everything involved (heavier cars, regenerative braking, rich young guys driving faster, mostly city driving, ...) is 15-50% more tire wear per mile.