As the owner of the vehicle, you can run any combination of tire types that you like as long as each axle tires size is close to the same as possible. You car will drive weird and be unstable and any warranties associated with any moving parts connected to these different tires will be null and void, but because you own the vehicle you can do whatever you want to do to it.
Flats are a shoe that does not have a high heel on it. Or they could be talking about flat tire.
There is no absolute way you can prevent flats.
i am told flats cant be fixed on the 370z
In the United States there are seven tire punctures every second, totaling 220 million flat tires each year
Some BMW's are fitted with 'run-flat' tires. If it is, it is not provide/sold with a spare tire because the 'run-flats' will allow you to do 90 miles on a flat and this will be enough to allow you to drive to a garage and have the tire replaced (they can not be mended). In other words your BMW may not have a spare tire.
You need to get it off the road. If you've got a flat steer tire or you're running super singles--tires that are twice as wide as normal truck tires--they're okay with you pulling just to the side--they know you can't drive the truck with a flat steer tire or a flat super single. If you've got one flat tire on a dual wheel assembly, they want you to limp the truck to someplace like a rest area if it's practical to do so. (They're not stupid, though; if the next rest area is 95 miles down the road, they don't expect you to drive 95 miles at 30mph.)
If you have run-flats, you can drive for up to 300 miles under 50 mph and be fine. With a typical flat tire, it is not considered safe to drive, and you should call to get a pick up truck if possible.
Run-flat tires usually can not be fixed. The tires are usually $100 more than because they contain more rubber on the sidewalls & surface so they can run flat, therefore it they usually can not be repaired or plugged for safety reasons. For more information, call your local tire center. (Note: do not mix run-flats with non-run flat tires.)
Run Flats?
No, once it has a flat spot it will always have a flat spot. Replace the tire.
jack flat tire hammer
A full tire is heavier than a flat tire. When a they are both flat they weigh the same but added air makes the full tire heavier.