I actually like the ride of 15's, although 17's have all the pluses mentioned so far, but with 15's you can boost TP to stiffen them up, 17's are already and allways stiff, if you lower pressure in them rims will suffer. But the biggest issue, 15's are getting rarer, and that is unlikely to change. I say enjoy 15's while you can. Although some may read "old school" into this reply, I have 15's, 17's and 18" in my collection.