I'm among those who have raced 1/12th scale for a very long time and I've settled on two dramatically different tire combos for my 1/12th scale cars during the brushless & lipo era. Sometimes I find that black/grey works a bit better for me, but I usually prefer double blue/blue. My car does work well on either type of rubber, but my "hot tire setup" does seem to flip-flop back and forth and from week to week even at the same racing venue. Which family of rubber that works better for me seems to depend mostly on how heavy or not the turnout is on any given week. Having said that, if 17.5 1/12th was run on a spec tire, I'm confident that would cut my tire bill nearly in half. If spec tires were the norm, I'd no longer find it necessary to take a few sets of "option A" tires plus a few more sets of "option B" tires along with me to each race day. So I'm one who would be in favor of going with a spec tire on the basis of cost savings and simplicity. Black/greylo could be a viable combo for a spec tire package, as would double blue/blue. I believe that most any modern 1/12th scale car can be tuned to run well on either of those two tire options and on most any track condition. Could one tinker with additional tire compounds and find a few extra tenths of speed? Well, of course. But is that extra expense and added complexity of unlimited tire choice beneficial to the overall health of the class? Probably not. IMO, going with a spec tire could be of great benefit to the vast majority of 1/12th scale club racers who do share one common denominator..........racing RC on a budget.