When GoodYear told me they were not going to make the 31x12x15 [D2585] last year or this year, I called Hoosier about 12" slicks since NHRA JrFuel has a limit of 12" tires. They told me they make three 12" slicks, 31x12, 32x12, and 33x12, but he said the 32x12 is a soft compound, made for door cars, in that they need a tire that Hooks, shift, hooks, shift, etc. I know some of the racers racing 7.0Pro have won running the 33x12x15 Hoosier.
FED's with Powerglides, need a harder compound to keep the tire speed up so as to not hook and pull the motor down out of it's power range.
I would go with the harder compound for FED use.
BTW, I talked GoodYear into making a batch of 31x12x15, by pre-selling 180 tires which was delivered last Aug. if interested, I have a set of new GoodYears, and one or two sets of used for sale. This is the tire almost all JF racers use, running as fast as 6.76, 195mph.
Let me know if I can help, 805-444-4489
Jon