Are you talking fog or headlights? I don't believe they should be used for headlights and I think they are illegal in most areas as such. Yellow bulbs are great for the fog due to the contrast they provide, but they do no illuminate the road very well at all. I'd nix the idea for headlights, but they would work well for fogs - assuming they are legal for fogs where you are, and I see no reason why they should not be.
Also, just noticed you said "daylight bulbs". If you are talking daytime running lights, I see no problem, but would they also not be your night lights? I know that before I pulled my DRL fuse, my xenons were both DRL's and the night headlights.