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      03-15-2010, 07:15 PM   #21
Tom K.
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Drives: '07 328iT, '13 Boxster
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Quote:
Originally Posted by Dackelone View Post
Bmw probably changed the OE tire specs . I suspect this bc my car really rides Ok, for a car with run flats. I know every hates them, but I really find the ride OK. Only twice, on really rough pot hole'd roads - did I find the ride a little harsh. But over all I'd say the ride is quite good, for run flats.

bye,
David
The only difference was that starting in 2009 (at least in the US), BMW equipped some 135i cars with Dunlop SP01 tires and some with the previously standard Bridgestone RE 050A. Since they are both Y rated high performance summer run-flats, I wonder why the change in the '09 pressure recs.

BMW does seem to do some strange things with recommended pressures as my '03 Z4 3.0 called for 33/36 but the Z4 2.5 with the same 17" RE 050 RFTs specified lower pressures - 30/33, IIRC. As the Z4's ride was bone jarring, even without the SP, I pretended I was driving a 2.5 and opted for the softer ride. With one rotation, I managed 30,000 miles out of the stock tires (and never once ran off the road, even on the Dragon), so I guess choosing a bit more comfort didn't hurt.

Tom
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