Example
53 rear tooth 13 front tooth 04 thru 06 r1 transmission ratio in 3rd gear is 2.66
53 divided by 13 equals 4.0769 multiplied by 2.66 equals 10.8445 witch is the final ratio.
What I have done when I go to a track that I haven't ran before is ask someone (that you trust) that races a UMP or IMCA mod what gear ratio they run then add 4.4 to that. It seems to work really close.
Mod gear 5.83 add 4.4 is 10.23
Almost forgot do not round your numbers very far.
Bobby Layne
2011 MLS Champion