## 3 Results
### Reaction Strategies: Recommendations to Promote Tyre CPP Derived from the Interviewes
#### 3.4.2 Recommendations for Policymakers
This is also in line with Section 7 of the Federal Budget Code (BHO) on economy and thrift, cost, and performance accounting [13]. 2. Promote the development of evaluation procedures that comply with procurement law: The need for evaluation procedures that comply with procurement law was mentioned in particular in the interview on #2. Emphasis was placed on the desire for market-recognised assessment procedures. One option for their establishment is standardisation. Similarly, the interviewee of #6 addressed the need to specify law-compliant evaluation procedures due to uncertainties in law implementation. Specific labelling strategies regarding retreaded tyres were, for example, suggested by the interviewee of #16 and will be described in the separate section on these instruments below. In addition, the interviewee of #18 underlined the need for a trustworthy body to support the work with labels and standards:  
_'(a body) that confirms: if you take the label, you can rely on it because it is not possible for (public procurement professionals) to compare all the labels with each other. Public procurement professionals cannot do that. They do not have the time. '_  
Promoting the development of the evaluation process can rely, e.g., on standardisation mandates and policies on labelling as practiced in the past. The establishment of the EU tyre label provides an example for this approach. (The EU tyre label is mainly focussed on fuel efficiency, road safety, and external rolling noise, but not specifically on circular material aspects.) 3. Declare tyres as a priority product for sustainable public procurement: According to [54], sustainable procurement requires documented prioritisation. Multiple SPP 'priority products' have already been defined and published on the website of Germany's national office for sustainable procurement (KNB). Sustainable CE tyres can only suitably penetrate public procurement if they are also defined as a priority product, cf. interview on #20. 4. Promote the procurement of retreaded tyres: The recommendation regarding retreaded tyres includes both currently available tyres and the results of future-oriented projects, e.g., from Continental (see, e. g. [32]), which promise further improvements of tyre properties. Retreaded tyres appear to be attractive when speed is less relevant. Concerning large order volumes, the interviewee of #16 described that retreaded tyres are promoted by an increased threshold for EU tenders in favour of a national tender based on the declaration as a'social service.' In addition, two recommendations were derived to promote sustainable CPP also at the national level for retreaded tyres. The recommendation to policymakers is: advance a label for retreaded tyres at the European level. A related recommendation to _public procurement professionals_ has the following three elements: intensify the focus on opportunities to purchase sustainable CE tyres concerning retreaded tyres, as previously discussed, introduce mandatory justification if sustainable tyres are not purchased, and purposefully use standards in describing requirements for retreaded tyres. 5. Conduct a cross-procurement level information campaign on sustainable tyres, also addressing vehicle procurement: The interview series clearly showed an information deficit regarding sustainable CE tyres. As one interviewee stated:_'We haven't heard about sustainable types yet. Advertising is required. Advertising is important. [... ] If there is something, we (will adopt it), but someone has to say there is something. [... ] It would be interesting to advertise recycled types, but if there are any, I don't know. '_  
The interviewees of #16 and #17 emphasised the importance of raising awareness even more. From the interviews on tyre procurement framework agreements, the importance of different actors in the tyre procurement process and their various ways to influence tyre selection concerning sustainable CE aspects became clear.