I want to put 235/60/18 on my 2014 Chevy impala which has 235/50/18?
I doubt it. Those will be nearly 2" taller overall. If they did fit, the speed error at 60 mph (indicated) will be about 64 mph. What you want size wise would be a 215/55/r18. 740 vs 739 rpm. 215/60/r18 might fit but would still have 2 mph error at 60 but would be difficult if not impossible to locate. Throw some numbers at this calculator to see. https://tiresize.com/comparison/
You may be able to put them on and see but you are looking at about 1.8" taller tires. Expect at least some rubbing.
Actually, the 235/60/18 is less than one inch taller so just make sure you have enough clearance when you turn your front wheels lock to lock