Science aid

"HammerheadFistpunch" (hammerheadfistpunch) 08/15/2013 at 12:50 • Filed to: halp

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Does anyone know a formula or calculator for determining contact patch area of a tire?

I've been using !!!error: Indecipherable SUB-paragraph formatting!!! and a spreadsheet I made up for the conversions. Im trying to calculate ground pressure as it relates to PSI of a given tire size. The site references formulas in an engineering handbook but doesn't give them to me. I would love to incorporate the formulas in my spreadsheet to make it dynamic. Any help?

MonkeePuzzle > HammerheadFistpunch 08/15/2013 at 12:51

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take a guess, divide by 4, coz its a LOT smaller than people think

Arch Duke Maxyenko, Shit Talk Extraordinaire > HammerheadFistpunch 08/15/2013 at 12:54

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More than I or you ever wanted to know right here.

HammerheadFistpunch > MonkeePuzzle 08/15/2013 at 12:55

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my numbers are something like 73 square inches per set @ 35 PSI. Which put my ground pressure at 32 PSI, and I can get it as low as 15 PSI ground pressure at 15 PSI tire pressure. I want to be able to put in section width, aspect ratio, diameter, load rating and pressure and get a dynamic number, i.e. what is my contact patch at X psi?

RamblinRover Luxury-Yacht > HammerheadFistpunch 08/15/2013 at 12:56

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Checked my only handbook that might have had this: nope. You're probably as equipped as anyone here at this point.

HammerheadFistpunch > Arch Duke Maxyenko, Shit Talk Extraordinaire 08/15/2013 at 12:58

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fun reading, but mostly related to dynamic loads and I'm concerned with static loads.

Arch Duke Maxyenko, Shit Talk Extraordinaire > HammerheadFistpunch 08/15/2013 at 12:59

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When are your tires going to be static?

HammerheadFistpunch > Arch Duke Maxyenko, Shit Talk Extraordinaire 08/15/2013 at 13:01

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never, but in mud and sand im going slow enough that load transferes aren't going to play a big role.

Arch Duke Maxyenko, Shit Talk Extraordinaire > HammerheadFistpunch 08/15/2013 at 13:04

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Well in mud and sand all rules go out the window for contact patch. There you want wide, and the wider the better. Hence these bad boys, sand tires.

HammerheadFistpunch > Arch Duke Maxyenko, Shit Talk Extraordinaire 08/15/2013 at 13:06

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sort of, im trying to figure out what effect psi has on a given size (i.e. airing down). "=Bigger tires" doesn't calculate in my spreadsheet and since contact length grows as pressure is released (not width) its really moot anyway.

Arch Duke Maxyenko, Shit Talk Extraordinaire > HammerheadFistpunch 08/15/2013 at 13:09

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Well I wish you luck in your quest for this Voodoo magic. PV=NRT.

You can tell a Finn but you can't tell him much > HammerheadFistpunch 08/15/2013 at 14:01

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How close are you looking to get? If you are looking for a ballpark back of the envelope calculation would corner weight divided by tire pressure get you close enough? Obviously that doesn't account for any sidewall stiffness, but for non-runflats it might get you in the range.

HammerheadFistpunch > You can tell a Finn but you can't tell him much 08/15/2013 at 14:04

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its a pretty decent approximation