Can you replace 225 60 r16 tires with 235 60 r16?

Sure you can. But know that you alter the dynamics of your vehicle. Your speedometer will read 58.9 at a true 60 mph. You will have slightly less power, handling & ride will change, and you may have clearance issues. Stick with the OEM size to avoid all this.

I disagree with the slightly less power as well as most of the rest of the answer your car maker always adds room for size obsoletion in other words no one offers your size anymore. You can ALWAYS go up one size without ANY clearance issues.

Just for reference I was certified as a Triumph mechanic just after my 14th Bday in 1979. I have been wrenching on things longer than most have drawn breath. There is no loss of power just a perception of less power due to the slightly increased mass of the larger tires. but this would be so small only NASA style sensors could even detect it. In closing a change of 1/2 pound of air pressure will do a similar thing which is why most cops aren't stupid enough to write 1mph tickets because there to easy to beat in court.