Current tyre's are 18-9.5-8, but you might notice in the video that the tyres are changed to different sizes at times. I really dont need any more crap comments posted about china quads being bad, from my experience my own quad is really reliable, takes plenty of abuse and performs quite well with engine mods. So don't even bother posting about how your yamaha or honda is so much better, what do you expect if it costs more and no one wants to hear more teenagers talking rubbish and nosense, espically when they have never even removed a head gasket never mind give advice on tuning. But my chinese quad is fine and most ppl that have had both would agree the china bikes if you get a good quality one are well worth the money and with little tuning power gains are as gd as brand name 250cc quads