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      01-30-2013, 10:45 PM   #50
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Drives: bsm 135i
Join Date: Apr 2012
Location: Vancouver

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Originally Posted by Stohlen
Originally Posted by Wescuddles View Post
Tires, if aired to the correct psi, will be just as safe stretched or not in average driving conditions. Do you have any idea how difficult it is to unseat the bead on a properly stretched tire at correct air pressure? Try it.

Avoid potholes and curbs and it's not an issue - the only issue would be using a backyard tire shop.

You seem like one of those people that like to talk just to hear their own voice.
So what you're saying is as long as you avoid the danger you're fine. What happens when you don't see a pot hole, or something falls off the back of a truck and you have to swerve aggressively to avoid it, or someone pulls out into an intersection when you're going 50 mph through it and your before you can even think you violently throw the wheel to get around it, but instead of being able to correct it, you're tires lose grip and you skid into a light pole, oncoming traffic, curb, etc. Its insane to think you can just avoid all danger and be okay. Not only are you putting yourself and risk, but others too. Yes I'm taking this to extremes, but these are things people don't think about when making modifications like this.

Originally Posted by Adam135 View Post
Stretched tires are the new age ricer mod. Not only is it unsafe, your rims have no protection, and handling goes down the tubes. I honestly don't know how this became a fad.
I'm glad someone shares my opinion.
Someone said it better and I don't feel like typing an essay. From another forum:
"If you are further interested in this topic I suggest you pick up some basic literature on vehicle dynamics or google cornering stiffness.

The sidewall flex that everyone else is talking about is parameterized by cornering stiffness in the tire world. What it describes is the rate at which the tire will produce lateral force. Physically this can be seen as the initial linear slope of slip angle vs. lateral force for a given tire. Many factors affect cornering stiffness and the "stretch" or angle of the sidewall is an important factor. In testing the cornering stiffness will continue to increase until the angle of the sidewall approaches that of the tread section.

Construction of the tire itself will contribute to the cornering stiffness and things like tread compound actually play a much more important roll than the sidewall stiffness. It's easy to understand as sidewall flex but this is just one part of the interaction. For instance the relaxation time of each material included in the tire will have an effect. The stiffness of the summit in bending and in shear will have a large effect. Even the size of the bead mounted to the rim will have an effect.

As everyone has stated before some "stretch" may be good. In fact ALMS teams use it as a balance and tuning parameter. Take a look at the Pratt & Miller C6R's they usually run a wheel larger than the measuring wheel up front.

At the control end for the driver it's down to the required response of the vehicle. A vehicle with higher cornering stiffness will respond faster to input but will also drop off quicker at the limit (unless this is countered by material choices). Actually changes in mechanical grip are negligible unless extreme differences in cornering stiffness are had.

In the case of every street tire it will most likely be perceived that handling has been improved with higher cornering stiffness (especially by gear-heads). Until you run the risk of unseating the tire or scrubing your wheels handling will improve with stretch (as others have stated before comfort will not).

As with anything you can have too much of a good thing..."
BSM 2008 135i
-VRSF 7" IC -VRSF DP's -n55 mids -BERK race -ER CP -TIAL BOV -BMS DCI -JB4 G5 ISO -ST coils -STOPTECH slotted rotors & pads -SLeK lip
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