I'll go one step further, same F and R, same series of same brand. Each series will have, all be it subtle, differences in design particularly wet road performance. On average, I replace 2 rear for each front. When changing both F and R, consideration is given to what is available. It seems that the range of high load rating tyres for the ST has broadened judging by all the GT models (72W) available now. For me any would do the job, I just stay with what I am used to running, PR4's GT.