They're okay, but not great. If you never make your tires squeal or howl when cornering you'd probably never notice the difference (aside from the noise).
Yep, no issue doing 80mph on dry interstate as long as the temperature is below ~50°F or so (tire wear will be a bit accelerated driving interstate speeds in 50-65° weather and you're more likely to lose a stud or two).From what your saying I assuming with studs unlike chains its safe to drive highway speeds?
Michigan, Minnesota, and Illinois are the main winter states that ban them, but they're also pretty flat and don't spend as much time bouncing above & below freezing (whn it gets really cold, studless tires work as well or better).
But I'd expect to see more state ban studs in the future, especially since car tires are now the largest source of automotive particulate pollution and studded tires add asphalt dust to the mix...