30-33mm knobby tires on old Ksyrium SL road wheels

I have an old road bike with trusted Ksyrium SL Alu road wheels. I am thinking to convert the bike for riding well-maintained forest roads (no single track, no jumping). I have hundreds of miles these roads around here so why not use them; they have grades up to 20%, nothing crazy. Would I be able to fit 30mm or even 33mm knobby tires to these rims? The specs say 19mm rim width; fork width is not an issue. On roads, I used 23-25 mm. The type of tire I have in mind are e.g. the Schwalbe CX Pro (30mm) and Vittoria Terreno (33mm) (I apologize if I am confusing gravel cycling with cyclocross :) ). Nothing special about these two particular tires, just brands I've used before.