The Independent American Magazine for all Mini Owners
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monitor tire pressures and improve safety, because most flats/blowouts occur due to increased tire temperatures brought on by low inflation levels. Although at first the development of the run-flat tire was something only the tire manufacturers were working on, the design and development this new technology for automotive use has necessitated that both auto and tire manufacturing companies work together so that the vehicle will handle properly. In fact, industry experts predict that within a decade RFTs will be standard equipment on all new cars. The Benefits Of RFT Apart from the obvious advantage of never having to change a flat tire on the side of the road again, run-flats offer carmakers and car owners several advantages. The carmaker can save on design and manufacturing costs. In order to carry a spare wheel/tire in the trunk of a car, certain design compromises have to be made in the vehicle structure. Fuel tanks may need to be a little smaller or be placed in a different location. Stamping of the trunk pan is more complicated and requires extra tooling. Additionally, accommodation must be made for the stowing of the jack, wheel wrench, and spare wheel/tire. Even though most cars still carrying spares now utilize space reduction or mini spares, they still take up room. Plus, these items add to the overall weight of the vehicle, which affects overall fuel economy. This last item is a biggie. At a time when Federal CAFÉ requirements mandate a raising of the overall fleet mpg, any gain in fuel economy, no matter how small is a solid step towards meeting the goal, and it also allows the manufacturer to make up for other vehicles in their product line that may not deliver such good fuel economy, such as pickups and SUVs. The car owner also benefits from the RFT as standard equipment. They will appreciate the extra gain in fuel mileage, however tiny, and they gain extra luggage space. In the MINI, which is limited on cargo area to begin with, this is an important feature. Plus, the car owner gains the aforementioned advantage of not having to change a flat again, ever. In addition, with run-flats installed the driver will benefit from the ability to drive on a flat at speeds of up to 55 mph and for a long as 50 miles, providing ample time to find a car dealer or tire store for repairs. Also, when a blowout occurs on an RFT-equipped vehicle, it maintains its stability so that the driver is less likely to lose control. The advantages of fuel economy gains, and the ability to drive at speed with a flat are what make these tires so attractive to MINI owners who track their cars. It’s Not All Sunshine And Roses Although there are significant advantages and benefits to all parties when it comes to run-flat tires, there are several drawbacks. For the manufacturer, the weight savings and fuel economy gains that come from doing away with the spare and attending equipment are not as good as one might expect. This is because the run-flat tire, along with its specially designed support systems, TPMS, and special wheels is heavier by about 25 lbs or so over a conventionally mounted tubeless and it increases unsprung weight by about 100 lbs (more or less) per vehicle. Additionally, the RFTs and special wheels cost more, so manufacturing costs are higher, as are design and development costs since new cars have to be designed with the handling characteristics of the RFT in mind. For the consumer the drawbacks may also outweigh the advantages, the number one of which is no spare. Yes, I know I said this was an advantage earlier, but it is also a disadvantage since it means that if you do have a blowout in the middle of nowhere and you are more than 55 miles or so from help, you are stranded until a very expensive tow can be arranged. Because of their narrow and stiffer sidewalls RFTs have a much harsher ride than traditional tubeless tires and they are noisier – a lot noisier. For MINI owners, the noise levels are particularly noticeable as the boxy cabin design acts as a sound drum, magnifying road noise to almost unbearable levels. Repairability is also an issue. Many run-flats cannot be repaired if they have been driven any distance while flat. Even if they haven’t a puncture of more than about 3/16th of an inch the &XWDZD;\ YLHZ RI D %ULGJHVWRQH 5)7 VKRZV OD\HUHG FRQVWUXFWLRQ VLGHZDOO VXSSRUW OD\HUV DQG VSHFLDOL]HG WLUH EHDG GHVLJQ 'LDJUDP VKRZV WKH VKDSH RI D FRQYHQWLRQDO WXEHOHVV ÁDW WLUH OHIW DQG WKH %ULGJHVWRQH 5)7 WHFKQRORJ\ ZLWK VLGHZDOO UHLQIRUFLQJ UXEEHU :KLOH \RX FDQ GULYH IRU PLOHV DW PSK RQ D UXQÁDW GRLQJ VR FDQ FDXVH FRPSOHWH GHVWUXFWLRQ WR WKH WLUH DQG UHSODFHPHQWV DUH FRVWO\ Issue 32 MC2 Magazine 35