New to 1/12 scale and will be running on really big outdoor track , like the local nitro track so it has a long back straight , our first race will be in a couple of weeks so I need to buy some Spurs and pinions , I don't want to spend a million dollars on gears so I need to try and guess the roll out , the class is 13.5 Blinky and Iv got an R1 , my guess is about 90mm roll out but any other educated guesses would really help cheers