In the Langenscheid dictionary the word "rot" is transcribed as [roːt], that is, that dictionary is saying that the symbol [r] express the "r" sound of the word "rot". However, using table [1] (below), it seems to me more appropriate to use the [ʀ] to express the "r" sound of that word. For me it becomes clearer by looking at how the [ʀ] (see video [2]) and [r] are pronounced (see video [3]).

I believe this based on the video lesson [4].

Another similar question: Which symbol belonging to the IPA best represents the "r" sound of the word "Ort"? Is [ʀ], [r] or [ʁ]?

For me it's [ʀ] and for Langenscheid it's the [r]. But according to the video [5] the best symbol is the [ʁ].

[1] http://web.uvic.ca/ling/resources/ipa/charts/IPAlab/IPAlab.htm

[2] https://www.youtube.com/watch?v=5C3TlnUoYP0

[3] https://www.youtube.com/watch?v=1GR4zKYgROI

[4] https://www.youtube.com/watch?v=3C8j7y9VxUk

[5] https://www.youtube.com/watch?v=SNn0ORQPrtA