Mar 09 11
BMW have whole heartedly adopted run-flat tyres across their range (except M cars). The benefits of these tyres seem to boil down to a solitary point; that is, if you have a puncture at high speed (say on the motorway), the run-flat tyre will not explode and cause an almighty crash! Oh, I suppose an additional benefit (to BMW, as I’m sure that any cost saving was not passed on to their customers) is they don’t have to provide a spare wheel (not even a space saver). Whereas, back on topic, it is almost impossible for me to enumerate the issues I have with run-flat tyres;
- they are expensive,
- they cannot be repaired if you have a puncture,
- they cause increased road (and therefore cabin) noise,
- they cause a harder ride,
- they cause poorer handling (which is why M cars have retained non-run-flat tyres), and now
- they are a contributing cause to fractured alloy wheel rims!
Yes, as the tyre side-wall is so hard (strong) to enable it to be driven when deflated, it transmits more impact to the alloy wheel rim. For example, when going over a speed bump a bit faster than intended, or perhaps hitting a pot-hole, not only does it give you an even more jarring ride, but it can (in mine and many other people’s cases) fracture the wheel rim! BMW alloy wheels are not cheap to replace – and it must be replaced because it’s a MOT failure to have a cracked wheel rim.
To add insult to injury, imagine my mood after being told by a BMW main dealer that I should have gone over to normal tyres years ago when the run-flats, that the car is supplied with, wore out and needed replacing! The service manager said, “not only would it have saved money, it would be like having a new car with better handling and a quieter ride!” Not to mention that I might not now be faced with an expensive bill to replace a fractured wheel…