Yes, the seller was EZ Accessory. They shipped really fast (around 2-3 business days).

As far as 15mm, i shouldn't see a problem unless you are planning on running wider tires later on. I went with 10mm because I plan to run wider tires and I was afraid I would rub on the outer lip with 275 or 285 tires. But like I said, if you plan on keeping the stock tires then it would be perfectly fine.