Promo Codes in Steam

[Chiken | F]

I would like to play iRacing and I have a promo code but I cant pay on the official site of iRacing because I have no Paypal or something else and I dont want to use other ways(and I have money on Steam already). So I think it would be nice if you can use the Promo code on Steam al well as a 3 month trail

[Admiral Aerial]

you cant
they make you buy through their site