If you are running on a clay track, then I would suggest you not use Simple Green on your tires. Plain old H2O is best. I found that the car felt noticeably more planted when I didn't use anything but water.
I like Zip Free when the track is holding moisture and is grippy. If it's drier then I prefer Buggy Grip. If it's real dry and dusty the Buggy Grip may work but I'd go with a different tire and compound so it probably wouldn't be compatible.