I replaced the single tire with a non-RFT, Fierce brand (inexpensive off-brand, made by Goodyear I believe) which cost $120, and a $21.00 charge at Americas Tire company for the mounting. It is a visual mis-match (different tread) but the car handles and rides smooth and just fine on “normal” freeway and street driving. I use the car for transportation, not performance. However even at 85 mph freeway speeds I can feel no difference. I did have to calibrate the FTM twice, but it has stayed in calibration for three weeks and about 1,000 miles so far (long commute to work).

Were I to engage in aggressive driving, especially on tight curves, or on slick roads I might be concerned with the significant mis-match of the rear tires. I also don’t plan to rotate to put the mis-match on the front. I plan to run this configuration until the other three RFT wear out, then will replace all four with some sort of non-RFT.

While the independent shop where I bought the single tire could not remove the Bridgestone Potenza RFT because of the stiff sidewall, the Americas Tire store had no difficulty, and treated it just as any other tire change. As a note, I only brought them the tires and wheel off the car, thus no issue of them seeing the mis-match car mounting and any ensuing discussion of liability. I did have a discussion with the salesperson about the tires but he made no comment about replacing a RFT with a non-RFT.

By the way, my car does have a limited-use spare. The under trunk floor storage space is not deep enough for a regular wheel/tire or I would replace it. I am considering doing that anyway – the diameter will fit but the width will raise the floor of the trunk by about 3-4 inches. A small price to pay for the ability to continue a trip (we are often hundreds of miles from home) without the expense/inconvenience of finding a replacement tire (on a Sunday morning at 7:00 am for instance).

I just bought some nice RFT 17″ rims from an authorized BMW dealer and then got a tire guy to mount regular tires. He said It was just as easy as fitting tires to any rims, despite the extra hump on the RFT rims.

The computer doesn’t care whether you have RFTs or not. It just monitors sudden changes in the wheels diameter (from ABS data, I guess).

I had a puncture once (10 cm / 2mm iron spike directly into the left rear tire at 130 kph) with regular tires (Michelin Pilot Sport 235/45/17). The pressure loss monitor warned me instantly and I got off the highway before the tire lost enough pressure for me to feel the pressure loss at all.

Good radial tires do very very seldom blow up from a puncture. They tend to leak air, and with the PLM you’ll have amble time to get off the road.

Remember that in some countries BMW sells the 520i with regular tires and an emergency tire. So it can’t be that dangerous to run on regulars can it?

Never used RFTs – never will.

BMW: Why not make the “storage” well in the back of the car large enough to accommodate an OPTIONAL compact spare for those cases where we have a puncture (>150) miles from the closest BMW dealer (pretty much the only facilities who can mount the tires, let’s be real.)

Those of us who drive long distances in the country with a full boot of luggage could then have a backup plan.

Run Flat tires have proven their worth to me. Having a puncture in the mountains of PA, in a thunderstorm, surrounded by high speed lorries, my family was able to drive on into a town where we settled in to a B&B whilest I had my car flat-bedded to the nearest city for tire replacement. Two days lost true…but family alive and well.

BMW should have paid for my accommodation. My end costs were around $1400 for the hotel, meals, and tire.

RFTs are tricky, I have Continental also, a bit noisy, but I don’t mind them.