hello total newbie here to this site as well as to 4 strokes as i am/was a total diehard skidoo guy... anyway after doing some searching on here about idler wheel issues,as i have a few that seem to have bad bearings. anyway i am curious as to why there is only 3 large rear wheels? it would make more sence to me that there would be 4 of them for equal tracking but im sure the there is a reason for it... anyway the reason i ask is that the inner rear wheel on mine is shot and i was wondering if it would be better to add a 4th one while i was fixing it? there seems to be some very good yamaha guys on here and looking for some advice thanks johnson