Check the tire rule at the track your running. A lot of tracks are requiring a 50 on the RR. Since your running the clone engine I believe the Hoosier 12×8 D50 or the Burris 11.5×8.5 TX50 are the best for your class. That Burris 11.5×8.5 won us some races when everyone was running hoosier on a heavy track. When you move u to the 250 or 500 then go with the 12×9 on the RR.
You want the 12X8 (IF the track mandates the D50 RR - It is also offered in a 12X9.)
If they do not mandate specifically the D50 compound, then go with smaller tires.
If the track has a 50 duro rule -- the D30A will meet that.
These big tires were designed for the 250 and 500cc winged outlaw karts that can spin the tires at will.
They are way too much tire for the underpowered classes!
We offer a small treaded tire set that works very well with clones, animals, L206, etc on these cars and gets the right sides back to 34" circumference where they should be. We also offer tire cutting/profiling service should you care to go that route as well.
Feel free to give us a call if we can be of any help.