Regarding tires for the Model 3. People assume the same brand, same style tire behave the same no matter the size. Manufacturers can make widely different products under the same name. They can even make OEM and retail versions or multiple OEM and/or multiple retail versions of the same size tire. The OEM tesla tire on the 20" rim is using this name but is a superior tire to the retail 18" tire of the same name. 20" Michelin PILOT SPORT 4S 235/35ZR20 9/32 tread UTQG 500 AA A (TO Tesla, Acoustic Tech) 18" Michelin PILOT SPORT 4S 235/45ZR18 9.5/32 tread UTQG 300 A A (Retail tire) In the retail tire you don't get the acoustic foam, you get way worse treadwear, and a slightly lower traction rating. Both Tesla OEM All Season tires include the foam and have a higher tread rating 19" Continental PROCONTACT RX 235/40R19 9/32 tread UTQG 400 A A (TO Tesla, ContiSilent) 18" Michelin PRIMACY MXM4 235/45R18 8/32 tread UTQG 500 A A (TO Tesla, Acoustic Tech) and the retail alternative for the 19" has a higher UTQG traction rating than the 18" Pilot Sport 4S. 19" Michelin PRIMACY MXM4 9.5/32 tread UTQG 500 AA A (Retail Tire) UTQG glossary: Treadwear: "The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. A tire graded 200 would last twice as long on the government test course under specified test conditions as one graded 100." Traction: "Traction grades, from highest to lowest, are AA, A, B and C. They represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. The testing does not take into account cornering, hydroplaning, acceleration or stopping on a dry surface. Nor does it account for the significantly different effectiveness of ABS versus non-ABS braking systems on a tire's stopping distance." One other note about summer performance tires https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=273 Summer tires lose traction when the temperature outside is below about 45F. Consider this if you use summer tires on your car. Those are the 3 primary OEM/Retail tires that people talk about on the model 3. The OEM tires can come from the factory or be ordered after the fact. The retail tires can be purchased from the Service Center, the Tesla website, or other retailers. If you get the 18" Pilot Sport 4S you aren't getting Tesla OEM specific tires and they will not be equal to claims about the superior performance of the 20" version.