I have Windows 10 x64 with installed latest Visual Studio 2015. I needed v141 build tools so I downloaded and installed Visual Studio 2017 C++ Build tools. Anyway the the IDE still showing only v140 in Platform Toolset listbox in project settings.
I checked if it's installed and it's contains core tools, mstools and tools v141.
Best Answer
Platform Toolset V141 is from Visual Studio 15 2017 not Visual Studio 14 2015. Basically, the software is backward compatible but not upward compatible, so when you have multiple versions of build tools installed, the most recent one can also use the toolsets provided by the older ones.
In other words, after installed toolset v141, the toolset v141 is added to that list of available toolsets in VS2017 - but not in the other VS, e.g. VS2015. So the v141 will not shown in Visual Studio 2015 Platform Toolset listbox in project settings.
If you want to use v141 build tools, you could install the Visual Studio 2017 and update your project to Visual Studio 2017. In this case, you can still use the old build toolset v140 after install v140 toolset: