this should do the trick
I have the MT2 18SS my self and i have the same problem. I set the dial in the transmitter in the middle and then i took the rod that goes from teh servo to the truck its self you will know waht I'm talking about and i twisted the ball cups in as much as they would go on both sides and then i put it back on and then i un screwed the servo arm from teh servo and then i put it back on where the tires are set straight and then i screwed it back in and then it gave me much tighter steering.