Drifting, hellaflush, slammed, tire stretch blog/bash thread.

[sofaking]

Since I clearly don't understand how to apply a torque to offer a direction because I thought it could be used as a force I wouldn't know how to add it. For the sake of this analysis lets say the tire is static.

I read the FoS link, interesting stuff. To my knowledge (making an assumption without taking hours of classes on the subject)... Passenger tires would have an MoS of +3 or +4 if the sidewall lasts 3-4 times longer than the predicted load, correct? Not to mention that any given tire usually isn't at its maximum load when installed on a passenger vehicle anyway (Which is what the FoS is engineered to. I.E. max inflation pressure/weight), correct?

Also the article covered a sentence on my point as well...

Many systems are purposefully built much stronger than needed for normal usage to allow for emergency situations, unexpected loads, misuse, or degradation.

This would lead me to believe that it is possible I am right. I'm not saying that it is or isn't "safe". I'm saying that it's possible that it is safe, correct? If it is possible that it is safe, then the obvious conclusion would be that it would not be a fact to call it "unsafe", correct?

[vex]

Originally Posted by sofaking

Since I clearly don't understand how to apply a torque to offer a direction because I thought it could be used as a force I wouldn't know how to add it. For the sake of this analysis lets say the tire is static.

Roger. Now lets look up the material properties for the Rubber of the tire (we'll assume some generic vulcanized rubber). We'll also assume (for simplicity) the rim is solid (IE it is going to deform orders of magnitude less than the tire).

I read the FoS link, interesting stuff. To my knowledge (making an assumption without taking hours of classes on the subject)... Passenger tires would have an MoS of +3 or +4 if the sidewall lasts 3-4 times longer than the predicted load, correct?

No. The factor of safety is calculated using yield and/or ultimate stress criteria. Sidewalls may or may not have 3 or 4, but it is completely determined via structural criteria (not life expectancy).

Not to mention that any given tire usually isn't at its maximum load when installed on a passenger vehicle anyway (Which is what the FoS is engineered to. I.E. max inflation pressure/weight), correct?

No. They're engineered to load criteria IE; cornering loads, static loads, etc. Although max inflation pressure and weight due play a roll into deciding the static loads they do not fulfill the entire criteria for the loads themselves (thermal, adhesive stress, etc factor in as well).

Also the article covered a sentence on my point as well...


This would lead me to believe that it is possible I am right. I'm not saying that it is or isn't "safe". I'm saying that it's possible that it is safe, correct?

Not really. It would be similar to say that a non-firing round from a gun will never fire, which isn't necessarily true. There is a possibility that the round may never fire, but would you risk it (if you're a gun enthusiast)?

If it is possible that it is safe, then the obvious conclusion would be that it would not be a fact to call it "unsafe", correct?

It's arguing a logical fallacy. A car with a slow leaking break master cylinder is safe until you're sucking in air on the freeway--that is to say, no. Using a product outside of engineering criteria is going to be unsafe especially with the current trends of lean manufacturing.