You bundle the high margin stuff with low/no margin items with high value so you can profit.
If anything, I'd think the tires would have the lowest margin since Tesla is a pure reseller and has no value add on that item, unlike the others in the perf package (air suspension, leather interior, Tesla's proprietary powertrain upgrade).
I really have no idea of course, no special insight, I'd just suspect Tesla's biggest money makers would be the things they control rather than resell.