my thought was more tires produced for that size, should mean cheaper named brand tires vs the 15's that are produced once or twice a year, I only get to pick 2 or 3 of when I need them.

but yeah seeing that might not be the case.

I suppose I could also argue, that if I ever take it cross country and have a blow out, a common 17 inch tire would be easier to replace where ever I am at, vs a specific size 15 you have to special order.