But when it comes to to tires, I can say confidently, for the F104 you want:
- Pits Shimizu PS0572 R1 Hards for the rear
- Pit Shimizu PS00574 or PS0577 F3 softs/meds for the front.
- Black can Paragon is the only legal sauce. I fully sauce front and rear. Adjust, as needed, as traction comes up.
The UF1 guys suggested them, I tried them, Racer Robert tried them, and we can agree wholeheartedly that they work. And they work well.
For the FGX the choice isn't so clear, I have used the Pit Shimizu grooves, soft rear/med front. They work, but if you have read anything I've posted on the FGX, you will know that I don't generally get a lot of track time before I break it. Robert has used other combos, like PS grooves in soft/soft and different Ride combos. I will edit this when I get that info.
An issue that I think may come up with the FGX is the width. There is a 190mm maximum, the FGX is 190mm stock, while the Ride wheels will add a couple of mm offset. Again I will get back on this. Not sure if the HPI wheels have offset.
For the HPI, I assume that the same combos that work for the FGX will work, since they use the same tires. Not too many HPI's have run at Mikes yet. One that I do know of actually borrowed a set of mine, and L O V E D them. So of course I took them away and made him use the stock set. (what a guy!)
EDIT: Here is what Racer Robert says about FGX tires:
"My favorite tires for the FGX are grooved Pits soft rear medium front. Those tires provide the best lap times. Soft/soft gave way too much steering no matter what I did to the chassis to reduce it. Also tried some Ride tires super soft all around. They work ok but the lap times are not as good. As traction increases ride's might be the way to go.
Ride wheels will make the FGX too wide. Stock FGX wheels put the car right at 190mm I measured this on a set up board with just the wheels (no tires mounted) and it was right at 190mm in the rear. with the bulge of the sidewall or if you are running lots of camber it may measure slightly more than 190mm"
So let it be written, so let it be done.