I was able to get a 18.5 ring from Weber before I received my 22.5 WSM. Here is what happened the first person I talked to (I was just pricing them. Wasn't ready to order.) told me I could not buy it until I had a serial number from my WSM. I called back 10 minutes later and got a different rep. I explained what I needed it for and that person told me it would be fine and gave me a quote. Then finally I was ready to order so I called back a day or two later and the 3rd rep said I could not order. I explained that I was told by a different rep that it would not be a problem and that person put me on hold, talked to a "supervisor" and then got back on and placed the order without a problem. The moral of the story is: It can be done it just depends on who you talk to.