90/90 is equivalent to 3.25 in old format.
If comparing stock 3.00 with servis 90/90,
Better grip, better cornering performance, more stability at high speeds when 90/90 combined with 2.15 inch wide rim
Some people say this 90/90 is bad for wet grip but i have come down from Murree to ISL on Express highway in heavy rain and it didn't let me down.
and finally that 3.00 looks kiddish on GS. This 90/90 with wide rim looks classy