I agree with Chryco. That is a Keystone Klassic style rim. As far as I know, Keystone was the only one to make that style. I have a set as well.
How old are those rims??? From the 70's? 80's?
The only other company that I am aware that makes them is Cragar now as I think they bought over Keystone or the design. I have seen that rim advertised currently under Cragar. It even has a Cragar center cap but it is a different style cap. The cap you have looks like the Keystone style cap but a different center design. I wonder if it can be peeled off to see what's underneath, but don't do it!!!
Actually, I do remember on craigslist a set of Keystone Klassic style rims that had a different centercap/company logo....but I do not believe they were "WS"....
Back in the 60's and 70's, I don't know if there were knock off style rims, for instance other companies had styles similar to the Cragar S/S or Torq Thrust but were marketed under other names like Western, ET, etc...