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Old 07-25-2021, 03:25 PM
oldskewel oldskewel is offline
Join Date: Nov 2014
Location: SF Bay Area
Posts: 1,423
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Originally Posted by andrewwynn View Post
I have square setup but that doesn't matter. Contact patch is force (weight) / pressure. Wider tire just means less length front to back.

It's worth the $ to get a weight measurement on your truck to know what the axles weigh with a typical load then do a little math and see how big your contact patches are. It's not ideal to have exactly the same as more weight will be helpful to have more tread on the ground but if you like to corner fierce like I tend to, finding a balance that is not entirely understeer is a good thing.
That simple formula would be correct if the tires were balloons, with no structural rigidity. Reality is a lot more complicated. The following page I just found (top of the list when I googled your "Contact patch is force (weight) / pressure") goes into a lot (too much in some places?) detail on this, comparing with experimental data from a tire manufacturer. It's easy to get lost in the details he presents, but it all makes sense, and much closer to reality than the balloon model.
2001 X5 3.0i, 203k miles, AT, owned since 2014
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