Hi guys. I'm sort of windows shopping for a Model S and it has been very interesting to read the adventures of owners experiencing the car in harsh winter climate. Since I live far north, this matters to me. It is a little unfortunate that the Model S only comes with 19 or 21-inch wheels. The range of winter tires in those dimensions is rather limited and very expensive. But I wonder if perhaps 18-inch wheels could fit. Has anyone physically tried fitting 18-inch wheels to their car? The limiting factor to downsizing wheels is typically the brakes. The disc and caliper needs to fit inside the rim. The rear (largest) disc of the Model S measures 365x28 mm. I compared with the BMW M5 (E60) and it turns out it has much larger brake discs: 374x46 mm. Yet the M5 can be fitted with 18-inch wheels. BMW even sells 18-inch OEM wheels for the M5. So unless the calipers of the Model S are significantly bulkier than those of the M5, 18-inch wheels might actually fit. That would open up a much broader selection of tires in dimensions 245/50/R18 and 225/55/R18.