Question to the used car dealers –> Warranty

Hello and good morning, I have a question for the used car dealers here. I am currently operating a tyre service as well as a car trade. The latter, however, so far only with new vehicles. However, as more and more requests for used vehicles come I think about an extension. My question to you: How do you minimize your risk which arises from the warranty? Additional sale of a warranty insurance? it only take over the part (possibly excess of the insurance) which is not covered by the GV? Or do I see this wrong and the GV does not jump in in in the warranty case? If yes, with which guarantee insurance did you have good experiences? Thank you already times and nice greetings.