Gas tank size vs towing capacity

Can anyone explain why the larger gas tank on an 2018 tundra would decrease the towing capacity by 1,000 lbs? it's only maybe 80 lbs of additional gas.... so I don't yet get it. Also, it looks like the larger tank can be swapped into a tundra with the smaller tank without structural changes, so It kinda makes me scratch my head. I am *4 in the below table from the owners manual, and wondering why my trailer weight rating is 1000 lbs less than *3 when I think the only difference is 80-ish lbs of gas between the two trucks.


I did try to search and didn't find related threads.

 

Interesting question and one I can't answer. I do know this which I learned from selling boats. Manufacturers rating on capacity are often quite conservative to keep them out of court rooms.

And in some cases other manufacturers claims are so high that a vehicle would truly be unsafe in towing or payload at max mfg rating.

Some of it is king of the hill advertising and other are cover our butts figures to ensure their vehicles are safe.

 

You have a platinum all of which have the 38 gal tank, the only ones with the 26 gal tank are the SR and SR5 without the upgrade package,they are a lot lighter than your Platinum,that's why the difference.

 

Hmm, Makes sense if the Platinum has all the extra weight in added on components, That would make the difference if the other trucks with the 9800 trailer weight rating is an SR or SR5. Moon roof, cameras and sensors, Lg gas tank, sliding rear window etc.... all come with added weight.

I was thinking the similar model numbers meant similar trims aside from gas tank but obviously not.

Thanks.

 

I can live with the tow capacity reduction. The reduction in payload is the real kick in the ass. These trucks normally max out PL way before TC.