A few sources have shown that the cars at the Model 3 unveil had 20" wheels with Michelin Pilot Super Sports in the following staggered sizes: Front: 235/35-20 Rear: 275/30-20 The wheels are probably: Front: 20" x 8.0" Rear: 20" x 9.5" These wheels/tires are undoubtedly an upgrade option. But based on the outer diameter of these tires, it's pretty straightforward to speculate about the standard wheel and tire size. For both the S and X, the front tire width in the large wheel option is the same as the standard tire width; 245 and 265 mm respectively. I think the same will hold for Model 3 and the tires will be: 235/45-18 The wheels will probably be: 18" x 8.0" There's a good chance the tire will be the Michelin Primacy MXM4, the same as the standard Model S tire. These go for $255 from Tire Rack. Here are a couple of other options with a similar diameter, but they don't make as much sense: 245/45-18 --This is possible, but they wouldn't have a wider standard tire than the optional large tire option. 220/50-18 --This is pretty narrow for a sport sedan that has the power to do 0-60 in <6 seconds 215/50-18 --This is too narrow for a sport sedan that has the power to do 0-60 in <6 seconds 235/50-17 --This works if the wheels are 17", but I think they'll do 18" for the standard wheel. This is more sidewall than is desirable or typical (4.6" vs 4.2" for the 235/45-18). What does all this mean? Not much unless this speculation is confirmed by Tesla. But it might help if you're looking for summer performance tires to replace the 18" OE tires. Also, it might help if you want to price out winter wheel/tire packages.