If You Are Behind A Truck Can That Truck See You?

Trucks rarely have eyes.

The truck driver can see you only if you can see the mirrors on both sides of the cab. If you don't see those, you are too close.

One truck I was passing had a big sign on the side of the trailer near the front that said, "You are in my blind spot." It was pretty scary, actually.

You pretty much have to assume the truck driver cannot see you if you are beside their vehicle. It would also be a good idea to assume they can't avoid you if you cannot see their entire vehicle in your rear view mirror. (Even then, it may be problematic.)

That depends on the truck! Presuming you are speaking of a semi truck/trailer, you need to be able to see his mirrors,this way he/she will be able to see your vehicle.