road restrictions

someone needs to explain to me why on the radio they always say "snow tires AND chains required on route....." when they ALWAYS mean snow tires OR chains required.

now as far as I understand it there are 3 types of restrictions
1) snow tires. if you don't have snows you have to chain up
2) chains on 2wd, and if you have a trailer you have to chain it
3) chains on everything, 4wd, a trailers.

so whats up with these morons saying snow tires AND chains? the way I understand it is if I put a chain on racing slicks they are 'certified' for winter driving.

check out our road conditions nevadadot.com as of this posting we have over 50 restrictions.