BETTER than BMW's Extended Warranty
Geico has mechanical break down insurance coverage. It has a straight $250 deductible. Only for new cars. After the 4/50 warranty runs out, you can do mechanical repairs and only pay $250 per repair total. So it protects against any big repair bills. It only costs $70 per year and lasts up to 7/100, just like BMW's warranty.
For wheels/tires, they tried to sell me on a 5 yr warranty that would protect tires on a pro-rated basis if they got damaged by road hazards. It's not worth it. (It was $900)
To protect your wheels, get full coverage. Most insurance companies cover wheels in their full coverage. Unlike the dealer tire/wheel warranty, insurance even covers cosmetic damage.
To protect your tires, buy from Costco. They give free road hazard protection. Or you can buy it from an online dealer like tirerack.com