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Old 02-07-2013, 06:29 AM
Pinecone's Avatar
Pinecone Pinecone is offline
M Mad
Location: Maryland
Join Date: Apr 2002
Posts: 10,479
Mein Auto: M Roadster/M3
1. Very stiff and thick sidewall to support the tread off the rim without air.

2. Because the sidewall folds and to the two parts rub against each other, it damages the sidewalls, thus they need to be replaced.

3. Oh well.

4. This is always a good idea. As a tire ages and wears, the traction characteristics change. And in doing so, you can change the vehicle dynamics to cause issues when you need the performance.

5. No idea.

BTW a number of BMWs and other cars did/do not have spares, even without run flats. Our M Roadster, E46 M3, and Fiat Abarth all are spareless, without run flats.
Terry Carraway

'95 Alpine M3 LTW
'00 Dakar M Roadster
'02 Topaz M3
Red/White SRF #4 (Chassis 561)
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