Replace run flats - why?

I am thinking about buying a 2006 325i, and the reviews I read on the web seem to unanimously state that the cars are specifically designed for run flats only. Can anyone out there verify if this is fact or fiction?

Based on what I've read, they provide a harsh ride and are very expensive to replace.

So, what's the deal?

You have a place for a spair tire? Don't forget you'll have to get one if you have run flats.

i work for a bmw dealership here in nj,and yes in 2006 ,bmw went to run flat tires,which is why all bmws ,have a tire pressure monitoring system,but not all bmws have run flat tires,nobody checks tire pressures monthly as they are supposed to due to changing air temps ,so if a person was to get a flat ,they would never know,so with run flats ,you can drive safely ,but the tpm ,would set a warning light on the cluster of the dash advising of a tire problem

Nice car! Can go for it without any hesitation.

I have a 2006 325i and i got one flat tire and replaced it with a normal tire and have not had any problems

But I keep a "spare tire in a can" just incase

Thats a myth. You do not need runflats. I have a 07 335i coupe and i replaced my stock 18" runflats with a set of 19" aftermarket rims and non-runflat tires. The ride is better with non-runflats, but everything else is the same. I also didnt bother with a spare tire since i have AAA (and there isn't a place for the spare tire anyway unless i took up the whole trunk). You will want to keep your TPMS sensors no matter what.

If you get a lease, i HIGHLY recommend buying new tires RIGHT away and keeping your run flats in the garage in a bag. You have to return the car to BMW with runflats (unless you buy it). Depends on the car, but the run flats for my 335 were $400 a tire, so saving them for when you return it is a wise idea.

This is the top reason I haven't replaced my 2001 325i with a newer model. I think BMWs switch to run-flats was a bad idea. They are expensive to maintain (replace often, and costly), plus you have limited choice in tires. Personally, I would prefer a doughnut over RFTs. If I were to buy a new one, I'd replace the RFTs with regular times as soon as they wore out - which from what I've heard - doesn't take too long. Just my 2 cents.

In answering the poster's original question, I cannot see a reason why a car would only work with RFTs or what possible design could depend on RFTs only. In the end, they are just tires. As long as the TPMS isn't affected by regular tires, I say go for it.