The problem with the steering
 

Hello I have a 2008 Lancer DI-D and I changed tires Yokohama 215/45 on 18 with some Dunlop SP Sport Maxx 225/40 to 18, and after a few weeks has strengthened steering suddenly, and we changed tires, I put 215 / 45/18, I changed oil, power steering, I checked the power steering pump so good, but much is still direction, steering box told me that he has nothing, I do not know what to do, I turned to forums outside the service that are oh they are just filters and oil changed.

Help me :(

Did you turn the wheel until each end side ? many many time to do and seeing if always oil on the steering tank.

I checked and the pressure in the servo pump so good, the service guys took it to a test but to them it seemed that not much servo but you know that I take the car 4 years and I give account as is.