I notice that the ride is pretty rough and feel most of the road bumps compared to 16's. Not complaining but just an observation. I prefer the ability to corner like crazy than a floating luxo-ride.

 

I find the Dunlop run flats to be quieter than the OEM 17" wheels that were on the 540. The ride quality is also better. However, there is a lot of difference in the overall quietness and suspension between the two vehicles, so it may not be a valid comparison. Overall, if I change tires from run flats, it will not be because of noise or ride.

 

My ride has improved significantly with Goodyear F1 tires and 19" BBS wheels. This combination cut 56 lbs of unsprung weight off the car. The car feels quicker and the steering is more responsive. The handling is considerably better, especially over uneven surfaces because of higher performance tires and the lighter wheels.

The runflats are about 10 lbs heavier per tire because of the additional rubber in the sidewalls necessary to maintain integrity with zero air pressure. If you're willing to trade-off the risk of having a flat tire with the advantages listed above, then go with some better performance tires. If you don't want the risk, go with the runflats.

 

Rudy, as my runflats got used past 2000 miles, there has been a gradual increase in wheel hop under high torque and the 'step out' as you call it happens every day on the same left turn with a bad seam between two asphalt surfaces (@ 30-40 mph). This small hop didn't happen untill after a month of daily driving. Yes, I try to push the car to the limits when I can, but as the tires wear (quickly) down, the sensitivity to irregularities of the road increases. Handling when new was as good or better than a 530 with non-runflat Michelins I drove at the BMW Performance Center track a few months back. Since then, the run-flat tires on the rear of my 530 are breaking free more often. At the BMW PC, breaking free was difficult to do on dry pavement at higher speeds. I am planning on non-runflats asap. The ones I have are Portenzas at factory pressure.

 

The hop or step out most definitely happens if there is something that upset the balance of the car -- like a bump, expansion joint, or any other flaw in the road surface.

As you've seen, under these circumstances, you don't need to be anywhere near the limits to experience what I'm talking about.

I'm going to have to think hard about what I'm likely to get as replacements....

 

My main point was that the performance of the tires noticably deteriorated in a few thousand miles. It makes me cautious in the rain now too. At first, wet road handling was excellent. I am worried the tread on the rear has worn too fast and water rejection is also worse. I had no idea I should measure tire wear in a few months. The tread groove depth was small when new, but the amount of rubber contact area is so high on these wheels, it may be a design feature. My concern for the tire performance began when the dealer told me the tire was intended to last 20,000 mi. My life experience with tires was that they last half their design or warranteed life. Granted, I choose high performance (soft) tires when I can. These run flats don't seem to have a soft compound. Anybody have an idea about this? It has not been a topic here. My reference points would be Goodyear Eagle, Michelin TRX.

 

2,000 miles and all those problems with the tires! Doesn't say much for Bridgestone Potenzas. Do you think you may have damaged them at the Performance Center?

 

I don't think they were the tires he used at the Performance Center. As a matter of fact, I don't think they'll let you drive your own car there, they only let you thrash around in cars owned by BMW!

 

I hope my tires will last longer than 2.000 miles or else they will have a problem with me.. I normally have 15.000 miles on tires before I get to think about replacing them.

 

The Ride issue has not been a problem with me, however what I have noticed with about 12,000 miles on the run flats is they are LOUD !! It sounds like I'm driving a 4x4 with mud tires. Not pleased about that ....