Do not drive when tired. It is very good advice. I once fell asleep and destroyed my car.

Wow. Do not drive tired... What should we have on our car wheels? Blocks of butter? Ice Blocks? ;) We will slide there. I agree that tiredly sound wrong. We say "Drowsy driving." or less often, You snooze you lose.

Grammatically? Yes it sounds weird. Maybe to say "drive tiredly" sounds as if it is a deliberate action (ie. you have other options). I suppose it's too tied-up with the action, so "Do not drive when tired" makes more sense.

Yes outload i say YOU ARE RIGHT..lol .I also got really tired saying everyday to my brother to reduce the speed down while driving ..

I feel the same way as you.