Confused about aluminum dimensional thickness

I’m interested in a skid plate for my Mazda 3 that I’ll be using for rallycross. I’ve read various advice indicating that the minimum thickness should be. 1/8”. Corksport makes a skid plate for my MZ3 that they describe as 11 gauge or .090. I’m wondering if these are all equivalent. This chart seems to indicate that they are. http://www.metaltrone.com/metalgauge-chart.pdf

Obviously .090 is not the same as 1/8” which as a decimal is .125. Is this dimension for aluminum kind of like a 2x4 not actually being 2x4?

In short, will Corksport’s 11 gauge skid plate be suitable for rallycross?

TIA!

No. .125 is not equivalent to .090. Sheet metal tolerances are here. https://www.engineersedge.com/materials/sheet_metal_gauge_tolerances_chart_13178.htm

Looks like thickness tolerance is .0045 to .005 (depending on width) + or -  

Thanks for making me look that up. Sometimes I miss being an engineer. 

Should be fine, since courses must be navigable by stock vehicles without reasonable risk of damage.

Also, because reasons, steel and aluminum sheet gages are NOT equivalent.

Various varieties of different types of Aluminum with have different strength properties also. You might be able to go a little thinner with 7075 than 3003..   Or something like that...    

It is also going to depend on the attachment points and how they are designed.  

I'm not really convinced you need skidplates at all for rallycross in 99% of vehicle/venue combinations. So whatever you put on there will be more than enough. With an actual mz3 I might want one because lower ride height (I assume) but for a base model I'd just run it as is. I've never bothered with skidplates except one tiny one to protect a plastic oil filter housing from getting pelted with rocks, and none of the few failures I've had would have been prevented by a basic bolt on plate.

I just remember one of the old aircraft maintenance hands tell me that aluminum comes in two thicknesses-- "oh too thick and oh too thin"

Duke said:

Also, because reasons, steel and aluminum sheet gages are NOT equivalent.

 

Isn't it something like the "gauge" is how many foot-square sheets weigh a certain amount?  I was thinking a pound, but 16 square feet of 16-gauge steel (or, since  16 gauge steel is 1/16" thick, a one inch thick foot-square block of steel) weighs a lot more than a pound.

I could probably look it up, but conjecture is more fun.

Use of gauge came from wire production and the higher number for smaller wire came from the higher number of die-draws needed to get it down to that size.  Sheet metal gauges "sort of" followed the pattern, except they didn't use the same pattern for different materials.  That's why 16 gauge aluminum is thinner than 16 gauge steel and 16 gauge galvanized is thicker than 16 gauge plain steel.  Except for copper sheets.  Copper thickness is described by how many ounces a 1 foot square weighs.  Then there's shotguns.  For a 12 gauge shotgun, it takes 12 lead balls the diameter of the shell/breach to make a pound, or 20 balls for a 20 gauge shotgun, except for a .410 shotgun. 

In reply to djsilver :

Must have been shotgun shells I was thinking of.

makes you shudder... there are 4- and 2-gauge "stopping pistols" out there.  If that follows the same pattern, that's a quarter pound or half pound of lead.  Bet it shatters your arm just firing the thing, but it's better than being stomped by the Cape buffalo that is charging you..