Quote:
Originally Posted by Wescuddles
Please, enlighten us on how stretched tires are a con for everyday use.
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You are eliminating the tire's sidewall from the equation when you stretch the tires across the rim. A tire's sidewall is designed to be able to fold over in a sense to either side when cornering. An example of what I am referring to is seen in this video at 4:43.
The ability for the sidewall to flex in this manner allows the tire to hold traction through a corner during weight transfer. You want the sidewall to be stiff to hold the tires shape, and still able to flex the tread in this manner to keep proper contact with the road. When the tire is stretched the sidewall is forced into the position it would be when the weight has already been transfer during the turn, and in some extreme cases even beyond. So when the weight is transferred to that tire during a turn the tire loses traction much more quickly and the car is more likely to skid. This is especially important any time you are trying to avoid an accident using defensive driving; i.e. when you suddenly must avoid something. With less traction you're much more likely to be unable to avoid the object or skid into it instead of driving around it.
In addition to the loss of traction and increased understeer with a stretched setup, tire wear is increased on the edges of the tread, much like the tire wear you get when a tire is under-inflated for long periods of time. The tire is essentially wrinkled as it runs across the rim because of the stretching, even though you cant visibly see it. There is less pressure in the center of the tire than on the outsides when the vehicle is running in a straight line so the weight of the car is supported more-so on the outsides of the tires than equally across it. This causes reduced breaking distance, while minor, when compared to a properly sized tire.
Stretch tires also cannot absorb as much road shock from hitting potholes or bumps that a properly sized tire would, creating a harsher ride when driving and increased road noise feedback to the drive. Not to mention that it is much easier to damage a rim with stretched tires if you hit a hole than with a proper setup. The tire also does nothing to protect the lip of the wheel when parking next to a curb, while a properly sized tire extends slightly beyond the lip and could save some damage if you happen to scrape one.