After the hell I paid for not reading the fine print when I bought after market grip warmers (that ended up dying anyway) that didn't fit my 2015 Deluxe I now read the fine print on everything....you missed this part I think:
Features:

  • Can be bolted to a trailer or truck bed
  • Built in tie-down anchors
  • Fits all 15"-21" tires up to 140mm wide
  • Dimensions: 21"W x 24" D
  • Steel construction