After 15,000km the rear SP9000's are past their use-by date and need replacing. The main issue I would like to fix is the lack of traction, although any assistance with road noise would be great as well. So, I'm hoping that the members here can let me know: 1. What is the maximum legal size for a tyre fitted to the standard Typhoon 18" rim? 2. What tyre you feel will be the best performance/value for money combination? 3. How much or where I should shop in Brisbane. Thanks in advance.