By Patrick Rall
Bridgestone wanted to show off the advancements in their new 3rd generation run flat technology featured in the new Potenza RE960AS Pole Position RFT so they offered up a chance to make a few laps around a rough surface test track at Firebird Raceway near Phoenix. The comparison pitted two groups of 2011 BMW 328i sedans head to head ? one equipped with the standard Bridgestone Potenza RE960AS Pole Position all-season performance tire and the other fitted with the new Potenza RE960AS Pole Position RFT.
For those unfamiliar with run flat technology, companies like Bridgestone offer tires that have structural sidewall properties to allow the car to travel a safe distance in the event of a loss of air pressure. Where a normal tire that goes flat will quickly disintegrate while driven when the pressure is relieved, run flat tires have strong enough sidewalls that even when there is no air in the tire, you can maintain normal speeds until you can get the car somewhere to repair it ? or at least enough time to get to an off-ramp. One key feature of the 3G Bridgestone run flat tires is the addition of cooling fins along the side of the tire, which helps to keep the sidewall cooler in the event of a ?flat?. The cooler the tire remains, the longer the car can safely be driven before it begins to completely break down.
The problem with run flat tires in the past was that these hardened sidewalls frequently caused a rougher ride under normal circumstances ? driving some people away from the convenience of the run flat technology. However, Bridgestone is so confident in their 3G run flat technology that they had us drive the identically equipped BMWs through this rough course, having us intentionally hit the graded apex of the track first with the standard RE960 AS tires and then the same tires design with the run flat design. With older run flat designs, there would have been a defined difference in the harshness of the ride but with Bridgestone’s new 3G technology, the difference was negligible and to the average driver, it wouldn’t have been noticeable at all.
After we drove the new BMW 328i with the standard all season RE960 AS tires and the run flat versions, the folks from Bridgestone let the air out of the left front tire of our test vehicles and sent us back out onto the track. Unbelievably, there was very little difference in the feel of the ride or in the steering, with only a slight steering pull to the left side on longer straightaways.
Bridgestone’s new Potenza RE960AS Pole Position RFT featuring their 3G technology raises the stakes in the run flat game with a ride quality hard to differentiate from the average non-run flat tire.