I am running stock size Toyos on my 2015 SL (T1 Sport 225/45/18 front, T1R 255/35/20 rear) I am on my fourth set of this configuration.
Definitely much better grip and feel than the stock Kenda tires. The drive-line noise and belt squeal on the SS make noise comparisons irrelevant. Mileage is not the greatest, but I house my SS in the North Georgia mountains and at least 95% of my riding is somewhat aggressive, on twisty mountain roads. (For reference I didn't get any better mileage out of the two sets of stock Kenda I ran, before starting to experiment with other brands) I get approximately 6K on front and 4K on rear. Hope this is helpful to someone looking for an alternative on the stock rims.