10/49 for a tight track, 11/49 for a open track. 12/45 on a 10.5 with a mongoose speedo for 15 minutes is a ticking bomb
You
may get away with 12/45 on very small foams but with those big kit tyres on she's gonna blow.
Some have started to use the LRP SXX comp speedo which seems to be working very well indeed
