I run a well modified and dirt set-upped Mardave Cobra
(apart from the body,chassis and battery mounts,front arms and rear uprights,
there isn't a lot of Cobra left) on a similar surface to you.
Ribs(Proline wides on RC10B3 rims)up front without inserts aren't bad when it's very dry,Holeshots are good when it's damp.
On the back I tend to use Losi Ifmar Silvers with the stock inserts on RC10B3
rims in the dry.
They're a fine fuzzy type block pattern,which,coupled with 3 degree toe-in,
3 degree camber and 2 degree anti-squat give a good level of grip.
I usually run a 17t double,15t triple or occaisionally a 12t quad(all old skool brushed),
though with the triple or quad a good thumbfull of throttle coming out of a corner usually
produces a lurid but pretty controllable back-end slide if you're a bit rough on the gas
.
If its damp,I'll go to Holeshots or Bowties paired with a 19t single or the 17t double,just depends how
damp it is.
Either give more slightly grip than the Ifmars,but out of the Holeshots or Bowties,the Holeshots are slightly better.