## 1 Introduction  
Aircraft tires are used in different stages; these can be divided into taxiing, takeoff, and landing. During taxiing, the speed is relatively low, and therefore the tire temperature increases only slightly. During takeoff and landing, the temperature in the tread increases considerably due to high-speed friction between tire and runway [1]. However, the landing phase is the most burdensome and therefore defines the design specifications of the tire [2]. At the first touch between the tire and the runway, the tire has no rotational speed. Therefore, the tire heats up instantaneously, generates smoke from degraded rubber, and blackens the runway [3].  
For aircraft tire/retreaded tire manufacturing, the demand is to increase service life without many changes in the existing formulation and processing. From a compounding point of view, the selection of polymers, fillers, and other additives is crucial to address the Heat Build-Up (HBU) problem in aircraft tire treads and minimize trade-offs. Additives are generally used at relatively low levels to fine-tune the tread performance.  
A compatible and non-reactive hydrocarbon resin increases the Tg of a compound compared to the neat rubber [9]. The higher Tg of the compound raises the tan \(\delta\) value at 0 \({}^{\circ}\)C by more viscoelastic damping and thus improves the wet traction characteristics of tire treads built on basis of these compounds. Tan \(\delta\) measured between 35-75 \({}^{\circ}\)C is indicative of rolling resistance of tire treads: the higher, the more rolling loss, and this may slightly increase. At a temperature exceeding 100 \({}^{\circ}\)C, the tan \(\delta\) of a resin-containing rubber is lower than the one of the control rubbers without resin, which indicates low HBU: Figure 1. If the resin is partially compatible or if the loading of resin exceeds its miscibility level in the rubber compound, then a second peak from the resin is seen in the tan \(\delta\) curve [8].  
When designing rubber compounds with the use of resins, the properties of resins give valuable information about their suitability. The properties include:  
* Softening point which is indicative of viscosity and controlled by the average molecular weight of the oligomeric material;
* Glass transition temperature (Tg);
* Thermal stability;
* Viscosity;
* Solubility which depends on the resin type;
* Average molecular weight;
* Molecular weight distribution;
* Compatibility which can be defined as showing only one glass transition temperature within the rubber compound [10]. Compatibility depends on the resin type, molecular weight and its distribution, resin structure, and configuration.  
It is challenging to manipulate the performance balance of traction, treadwear, and rolling resistance of tires. These three properties are commonly referred to as the magic triangle for improving passenger car/truck tire performance. In aircraft tires, the properties of interest are low heat generation in the tread since this tire part is prone to temperature increase due to the extreme conditions. High temperatures are detrimental to tire properties: it can decrease the strength and accelerate treadwear. Therefore, it is crucial to develop a compound formulation with low hysteresis while maintaining other required properties. This manuscript explores how the use of resins helps to enhance processing, tackiness and final properties of aircraft tire retreads.  
Figure 1: Effect of compatible vs. partially compatible resins on viscoelastic properties [8].