There was a wildfire in unit 27 last year, right next to 15. That whole area is a sea of orange to begin with, and the fire pushed a lot of unit 27 hunters into 181 since a lot of tags are dual 27/181. This year, I expect a lot of "regulars" and "locals" who hunt there will also go into 15 since it's right there.
By the time 4th rolls around the deer are pretty shell shocked, that said there's a very high concentration of them. Be careful with maps. Not all the forest service roads are perfectly accurate where they start and end, and unit 15 also has some private land plots to avoid. In particular don't park on the private land especially on FS212 which is a common route in. (Parking along the sides of that road is limited but there are pullouts at spots.)
You should absolutely take tire chains, I would say that advice applies anywhere in Colorado. When dry a lot of forest service roads are like highways, and people will rip up and down them so fast they washboard the roads. But get a little water on them and that fine clay mud turns slicker than **** ******* * *****. Add a couple inches of snow, and chains start to look like cheap insurance. I hunted 27/181 last year and used my chains twice. There was a 9" or so snowfall in 3rd season.
15 and 27 are my wife's favorites. Y'all will laugh, but when we hunt there together we stay in Steamboat. Nothing says "glam-hunting" like a soak in Raspberry Hot Springs after a long day
There are a ton of deer in that area. Just be sure of your target. If ever there was an area ripe for a hunter-safety accident I'd say that's the one.