Nikkei Press estimated the market share of tire manufacturers in Japan in 2015. According to it, Bridgestone has the biggest share (25.3%). The industry-wide sales in 2015 were one million tons of tire.
Figure: 2015 Tire Market Share in Japan
|Manufacturer||Market share (%)|
|Toyo Tire & Rubber||12.9|
Source is Nikkei Sangyo Shimbun newspaper, the article on 2016 July 25th.