CarGurus should start a separate section for selling used rims and tires. Section should just show make, model and year period. Then attached a separate spec sheet with all the data about both the rims and tires which most info comes from owners manual unless someone changed from original equipment which then they would have a specs on the bill of sale. Make people fill out the spec sheet in full or they can't post.
Suggest it here....https://www.cargurus.com/Cars/enterFeedback.action
I disagree, there is E-bay, Craigslist and other sites that do that already.
Cargurus is in the business of Marketing dealers and generating dealer leads nothing else.