Hi Texas Grenadier, Although both a base station wagon and Trial Master have any rim and tire choice, for reasons unknown, the Field Master only rim choice is 18" alloys. I reached out directly to Ineos to change the configurator and offer the Field Master the same rim choices, however they responded that at this time there will not be any other choice on the Field Master for rims other than the 18" alloy. From spending a lot of time on configuring a Grenadier, if your looking to keep your price down and just choose a couple options go with the base station wagon, and configure up from there. However if your looking to get a lot of the options and don't care for the premium sound system and would prefer a second battery, then configure from the Trial Master. That way you have all rim / tire choices and I have found you save a little money and end effectively with some free items too. DaBull