best tyres ktm lc4 640

Could I have some advice re tyres for KTM lc4 640 sm prestige 2006 please? Had this bike since last July 09 and I use mostly 99% on road. Now want to replace both front and rear tyres. I'm now looking to replace them and I was thinking to PIRELLI SCORPION MT 90 S/T or also MT 80 R / MT 80...