I ran the 6 inside and 4 outside on my RX-1 which worked well. If you are an aggressive rider I WOULDN'T run the Simmon's on my SRX. I like them on my RX-1 because they add to the stability by making the stance wider and they provide a slight understeer which improves the handling. With the extra weight of the rx1 front end, wider stance and slight understeer, I think the ski creates the perfect balance for that sled. With the SRX I would worry about washing out, especially on loose snow. I recommend SLP SLT's for the SRX, they are a great all around ski. Less money too.