I have the Dunlop Sport Maxx those are summer performance tires. I think people people tend to complain because of a stiffer ride. I had an e53 for 9.5 years on regular tires. There have some that have made the switch to non-RFTS and have had issues it's been documented (and some of those tires are heavier in weight than the RFTs). The ride will no doubt be smoother with a non-RFT but I don't see how performance will be better unless you go to a non-RFT summer performance for that size like Yokohama (there are only so many tire manufacturers for the 20" size). I don't see how the Michelin Lattitude Tour or Conti Contact are going to be a better performance tire--they are designed for durability not performance.

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2008 X5 4.8
Jet Black/Black Nevada/Dark Burl Walnut
Adaptive Drive
Premium Pack
Tech Pack
Climate Pack
Sport Pack
20" Wheel Option
Premium Sound
Sirius Satellite
Rear DVD Entertainment
Multi-Contour Seats
Comfort Access
3rd Row Seat
Heated Front Seats
Running Boards
3M VentureShield Paint Protection Film