I'm not aware of vinyl-covered wire being sold for hook-up purposes. Most is PVC insulated. I don't think vinyl would be suitable. You're not thinking of regular lamp cord are you? That shouldn't be used inside a radio, except to just bring in the line cord.
Most people, I think, would find #18 to be a little too heavy, except maybe for a heater string. I prefer either #20 or #22 solid for most uses in an antique radio. I use stranded wire only for leads that have to flex, e.g., the wire up to a grid cap, but suit yourself.
The usual temperature rating of hook-up wire is 105 deg C. If you keep it away from power resistors, you should be fine.
RadioDaze sells hook-up wire rated for 600V and also unrated wire. With the antique-appearing cloth-covered wire, I prefer the unrated since the rated wire's insulation seems too heavy to me.
The original wire used in pre-war radios wasn't rated, at least like wire is now. I think most any hook-up wire you buy from AES, RadioDaze, or RadioShack would be as good or better than what was originally used in your radio.
:I am re-wiring an old 1940's Zenith console (in the chassis) and was wondering what type of wire to use. Most of the available flexible vinyl 18ga stranded wire is rated at 300volts. Is this enough voltage rating. Also is there a problem using vinyl coated wire with the heat generated under the chassis.
I think you're in good shape with that wire, even though you may decide than #18 stranded isn't too convenient. The original rubber-insulated wire was not good.
300V will be fine, in my opinion.
:I am using the 18 ga stranded wire from radio shack rated at 300volts. Doesnt the V in pvc stand for Vinyl? I noticed that when I soldier the ends the pvc tends to melt and shrink and thats what made me think about temp. Since the chassis is screwed down and the components are not visible, original is not important to me. I hope the pvc holds up better then the original rubber in the hot environment.