I understand you can get any of these warranties at anytime during the normal vehicle warranty. I did not get them with my vehicle purchase but I am strongly considering getting them before the warranty is up. There is no point in rushing though...
Considering how expensive even the simplest repairs are (my bud's water pump that went out in his E90 with 60k miles was over $2k) the extended warranty seems like a good idea.
I did not get the BMW Tire / Wheel Protection. I have the 19" style 309's and I have damaged 2 of them on the left side (1 leaks air and one is just not balanced anymore). I have no idea how I did this but I guess they are very fragile because of the low profile tires. It seems like a good investment. The 309 style 8.5" wide (front wheel) is $522 to replace.