which track will u race? for example: if u will race at Wan Chai small track with non turbo mode, 17.5R is enough. But for JV big track, non turbo mode at least 13.5R, 10.5R or even 8.5R.
maybe hydrogen9999 ching is a super expert then he suggest to use at least 5.5t, or even he can handle lower than 5.5t such as 5.0, 4.5, 4.0, 3.5 for the M05. i really would like to see his super skill.