I had 46x11 gearing on 40mm tires for many years and rarely wished for anything tougher. The rare times would be when I was on a long gentle paved road descent where it wasnt steep enough for me to just tuck and coast. Flat paved road- 46x11 was plenty with that tire size.
For the last year and a half I have used a 48x32 crankset with 43mm tires, so 48x11 is the toughest ratio and I have never wished for anything more. I will use 48x11 on flat road with wind at my back for short periods of time, but could easily just pedal a slight bit faster if all I had was 46x11.