I'm going to shorten Ian's post to make it easier to see what I am responding to:
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Originally Posted by IndyIan
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So wouldn't it be better to raise tire pressure to counter a common problem, hitting potholes and denting rims?
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There are 2 different types of impacts that I can discern:
1) A large object that compresses the sidewall to the point where the tire bottoms out against the rim flange - and if there is enough energy/object size/vehicle speed, the rim could be dented. In this case, more pressure would help prevent the tire from bottoming out. Striking a curb would be a good example. Needless to say, low profile tires would be more suspectible to this.
2) An object that is more pointed - but not sharp - where the ply cords of the tire are stressed due to bending (enveloping the object) and the result would be the ply cords breaking. This was the object of the test in the paper.
An example of this would be a chunk of concrete. In this case, it wouldn't matter what the aspect ratio of the tires is. The object size, vehicle speed, object shape would all be important factors in whether the tire would fail or not.
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How big a pressure spike can tires handle when hitting things like potholes? I can see how the pressure spike would be less with lower initial pressure but how much higher is the spike at 45 psi vs 32 psi?
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It isn't the pressure spike that is the problem - it's the stress concentrated around the object. BTW, the pressure spike is relatively small - a couple of psi as best I can tell.
This particular test has generated a lot of interest - and misunderstanding - so I modified the article to include a photo of the test setup and a different graph from the paper showing the height of the "nub". Sorry about the photo quality, but the copy I have is just as bad.