## 1 Introduction
### Motivation for This Research
\begin{table}
\begin{tabular}{c c} \hline
**Tyre Life Cycle Stage/Tyre Management Options** & **Relevant Rules** \\ \hline \multirow{6}{*}{Design and production} & Directive 2008/98/EC (Waste Framework Directive), its update by Regulation (EU) 2018/581 and the KrWG to consider the waste hierarchy already in the design phase \\  & Regulation (EC) No. 1907/2006 (REACH), Regulation (EU) No. 1272/2013, and Regulation (EU) 2018/1513 \\  & Regulation (EC) No. 661/2009, from 2022 Regulation (EU) \\  & 2019/2144 (type approval of motor vehicles and components) \\  & Depending on the application, Regulation No. 30 or 54 of the \\  & UN/ECE for passenger cars and trucks for type approval \\ \hline \multirow{2}{*}{Distribution} & Regulation (EC) No. 661/2009, from 2022 Regulation (EU) \\  & 2019/2144 (type approval of motor vehicles and components) \\  & Regulation (EC) No. 1222/2009 (type labeling in general) \\ \hline \multirow{2}{*}{Consumption} & Regulation (EU) 2019/2144 mentioned above \\  & General rules of the Climate Protection Act and the KrWG (e.g. part 5, §45) on public procurement \\ \hline \multirow{2}{*}{Collection} & Basel Agreement as a general framework \\  & Requirements for national take-back systems \\  & KrWG, AltafhrzeugV, Abfaev, NachwV, EfbV \\ \hline \multirow{6}{*}{Reduction and Induction} & KrWG, Directive 1999/31/EC on landfills, DepV \\  & Directive 2000/53/EC on end-of-life vehicles, AltafhrzeugV \\ \cline{1-1}  & Regulation (EC) No. 1907/2006, Regulation (EU) 1272/2013 \\ \cline{1-1}  & \multicolumn{1}{c}{Musterverwaltungsvorschrift technische Baubestimmungen} \\ \cline{1-1}  & and corresponding state building laws, \\ \cline{1-1}  & General rules of the KrWG on public procurement \\ \hline \multirow{2}{*}{Modification} & Directive 89/459/EEC \\ \cline{1-1}  & UN/ECE 108 and 109, The Council (2006) regarding the adoption in the EU \\ \hline \end{tabular} Note: In addition, the law of several Federal States requires the consideration of social aspects in public procurement according to ILO core working standards or at least the purchase of products from suppliers who ensure production without child labor. Special rules are also included in the SachsKrWBodySchG law of the Federal State Savony. More specific requirements on ELT management are specified in the guide “Leitfaden umweeltverfägliche Beschaftung der freien Hansestadt Hamburg” of the Federal State Hamburg.  
\end{table} 
Table 1: Key circular economy rules and regulations on tyres from a German perspective. This article addresses the CE aim of preserving resources at the highest possible quality. Specific emphasis is put on options 4 and 6 of [7], i.e., retreaded tyres and recycling. Particular consideration is also given to the replacement market for tyres. As shown in detail in the next sections, the paper provides answers to three questions regarding public tyre procurement in the EU Member State Germany:  
1. Which procedures are mainly applied to procure tyres and which selection criteria are mainly adopted in the procurement processes? 2. Which barriers exist to take greater account of the United Nations Sustainable Development Goals (UN SDGs) and the German Circular Economy Act (Kreislaufwirtschaftsgesetz, KrWG) in the procurement of vehicular tyres? 3. In response to the barriers mentioned in question 2, which strategies could support the procurement of sustainable CE tyres? To answer these questions, a Grounded Theory (GT) approach based on a multiple-case case study was chosen to understand barriers and possible strategies to stimulate circular public tyre procurement in Germany. This article is structured as follows: Sections 1.2-1.5 provide information on the key elements of this study, public procurement and tyres as well as relevant framework conditions for a tyre CE. Section 2 presents the study materials and methods. Then, Section 3 provides information on the cases, procurement patterns, barriers to procuring sustainable CE tyres, and, finally, solutions to address the obstacles on the basis of the interviews.