We are trying to find out where we can go to ask about advertising on Tuk Tuks in Bangkok.

Any help please ?

Ask a tuk tuk driver. He knows. The only people that benefits finical are the owners of tuk tuk's. You won't.

I'm curious too, I wonder how that kind of adverts even works tho, I agree tbh, probably only benefits them and not the company that's advertising unless it's a 1 time fee

The ones that read, "we break your arm if you don't pay us a lot of money for a short ride", might work,

I am not sure how it works now but about 15 years ago a friend of mine out of curiousity ask a tuk tuk driver how much he was paid for having a sign on his tuk tuk advertising a certain questhouse.The driver replied "a guy ask if he could put the sign on my tuk tuk I said yes, he didnot pay me anything"

Go to China Town. There seems to be more Tuk Tuk's down there than anyplace. If you need more info send me a PM.