Each bike is different. I have ran 73 Ro 14 extremes on my 4mm cub. Worked pretty good but i weigh 165ibs so I spun them like crazy. So now I have a set of 78 ro 14 staggered extremes on a 10" rim they seem to be working better for my weight. I'd go with the 73 Ro 14 extremes best all around tire IMO, Also works great with many motor combo's. Shayne is right it all depends on your bike setup as well. You gearing type of chassis mods and overall weight