The Porsche Carrera RED 63
('A' below) only needed 7 g and is the smoothest of the 4: on my 24 m Carrera track is clocking 8.84 s. It slides in a predictable manner and I am keeping it with 7g.
On the 3 others I added another 3.5 g in front of the motor because I was not that happy with 7g.
They are working much better now with 9g.
The White Trans Am ('B' below) which clocks 8.81 s (has the widest rear tires and you can feel a better stuck down feeling).
The Yellow 41 is clocking 8.83 (was 8.9 with 7 g) and is very similar to the Red Carrera 63 in handling..
The Blue and white Rally number 3 is the fastest one with 9g at 8.73 best time.
OEM tires are very good (newest Fly tire compound has nothing to do with, for example the Classic Fly one which was pretty bad!).
Off course I lightly sanded them.