Carpet Dye brown to gray/black

I picked up an inexpensive rear cargo mat and didnt' even think to ask if it was anything other than gray. It was in perfect shape and $15 and tan.

Considering trying to dye the mat to something in the gray to black color palette.

Anyone have any experience dying carpet with RIT or something else?
Any artists out there know if you can mix beige and blue to get gray?

 

I just attempted this and it was a mixed result. I used sapphire blue RIT synthetic dye and sprayed the carpet first with warm water and then with a mix of water and dye from a spray bottle. My mistake was not waiting for a warm sunny day and letting the sun heat the applied dye. Knowing it needed some heat I went over it with a heat gun and ultimately wound up with a light grey carpet with blue steaks. I am going with it as is. Close enough