Tyre emissions are roughly proportional to g-forces exerted by the wheels, so at a steady speed, on a motorway, without stop/start driving it's likely they are pretty low on both ICE and BEV. As we know most BEV tend to be heavier, so the baseline emission is probably slightly higher there but I doubt it's noticeable.I’d be curious to see the reduction in tire and brake particulate from lower speeds, it’s not only exhaust that is bad. EVs are a lesser evil but they don’t just emit candy floss. Noise is a factor too.
Brake emissions of course are on average lower on BEV because of regen braking - though the cars are heavier too .. so you win some you lose some.
There are a few studies that show that tyre particulates are generally much larger than particulates from ICE engines, so are much less likely to be harmful, and occur at much lower rates than exhaust emissions too. They tend to fall to the ground and are effectively filtered by the body's natural defenses. Unlike the mass of PM2.5 that comes out of a diesel.
I would not be surprised to find that reducing the average speed by 10mph makes a pleasant improvement on the quality of noise even if not particularly the level of it. I'm sure the neighbours would like it..