Autocrossers, what size tires do you run?? Im looking at 255/50/16 Mickey T's all the way around Any thoughts

Drag radials?
Unless M/T makes a tire for some type of road racing I wouldn't suggest those for autocross.
I am currently running some 275/45/16 Hoosier R6's, but I am running spacers front and back so they don't rub and wouldn't really suggest that size if you have an 8 in. wide rim. saying that, my next set of tires will be the 255/50/16 R6's
The tires that most autocrossers are using that have R comp's are the Hoosier A6, or R6, or the Kumho Ecsta v710. There are more good tires out there, but that is what most people use.

I run 275-40-17 (Kuhmo V700) on 17x9 w/5" bs, all the way around. It rubs less in front than a 245-45-16 did on factory rims. Back doesn't rub at all.

I am running 245 45 16 hankook RS2s i just picked up on clearance from the tire rack. if i had the money id be running the Kumho XS 265 45 16 but i could not afford them (cost twice as much) i drive my car to and from events so all out race tires were not an option. They have discontinued the RS2 in the 245 45 16 size, and the new RS3 only goes to 225 on a 16" wheel so the kumho's are the only option for those looking for a autoX tire that they can drive on the street for a 16" rim. The kumho tire beat all others in a recent article in grassroots motorsports.

We had someone show up with Mickey Thompson DR's at one of our events. They didn't last through the event. Don't do it.