Dirt Bike Tires

So its come time to put a new set of rubber on my RM250.
First set i've put on it since i've had it so im not too sure what to think. My mate has dunnie Geomax MX51's on his CR and i've ridden that and they go bloody well... but are they worth the dollars?

Can anyone suggest something cheaper/better??
I do probably 85% of my riding out the bush so the terrain is pretty varying.. and the rest is on my track at home.

I know being a 2 banga i dont just want the biggest, chunkiest barstards i can find, which is what everyone seems to point me towards.
So anyone got any ideas??
 
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