I've been doing some internetting this evening...

The rear wheel is a J 17xMT3.5 DOT and the typical sizes for this are 130 and (oversize) 140. On this chart on the MAXXIS website it seems to say that this is a normal size for a 140 tyre and that you could fit a 150 size tyre to a MT3.5 rim

The rear wheel is a J 17xMT3.5 DOT and the typical sizes for this are 130 and (oversize) 140. On this chart on the MAXXIS website it seems to say that this is a normal size for a 140 tyre and that you could fit a 150 size tyre to a MT3.5 rim