Since 2012, SMARTWAY certification has been mandatory for all steel tires in the retail market of tires in California, which is required for the driving wheels and guide wheels of vehicles entering the California market. The regulations were further upgraded in 2017 that the trailer wheel of the related vehicle in the retail market must be certified by SMARTWAY. This puts forward higher requirements for the rolling resistance performance of all steel tires. The development and application of carbon black coupling agent has reduced rolling resistance of all steel tread compound by 20%. The reaction mechanism is as follows: ①Amino group reacts / interacts with CB at non-productive mixing step. ②Thiyl radical generated by decomposition of  the thiosulfate group reacts with NR at vulcanization step.  

Generally, in order to improve the adhesion of rubber-brass interface, cobalt salt is added to promote the growth of the adhesive structure. But cobalt salt has bad effects on the aging performance of the tires. Adding cobalt on the surface of normal steel cords can improve the aging performance of tire using less cobalt salt which can reduce the cost and improve the environmental protection. In addition,  using TAWI can increase the adhesion of the interface.

Heat built-up is one of the main reason leading to the invalid of tire. If the TBR tire temperature rises 10 degrees, the tire failure rate will increase by 70%. TBR tires with thick shoulder and bead have large deformation and maximum heat generation. High conductive cords can quickly transfer the heat to the sidewall and cap, and reduce the temperature of the shoulder and bead.

Flat cord has a smaller diameter (short axis) and higher tensile strength, which reduces the thickness of the cord ply and the amount of rubber used, saving resources and reducing costs. Flat cord has a higher volume ratio in the tire belt ply, and the belt ply cord is more rigid, giving the tire better handling performance (currently in the tire performance verification phase).

Low hysteresis carbon black is a kind of reinforcing filler to adapt to the development of green tires, which can improve the physical properties of rubber and has some special characteristics that normal reinforcing fillers do not have. Low hysteresis carbon black can greatly reduce the heat generation and rolling resistance of the compounds, and endow the tires with good wear resistance.

In March 2016, California proposed a bill to restrict the use of zinc or Zinc Oxide in the tire, and it may prohibit the sale of a tire containing a certain amount of zinc. The bill is proposed because zinc poisons microbes and aquatic organisms. The use of vulcanizing activator with low zinc content is a trend. At present, our company has established the basic database and reserve formula of vulcanizing activator with low zinc content, and the zinc consumption in synthetic rubber can be reduced by 30 to 50%.