I believe that if you take the top and clamp it to the bottom 6-10” of a plastic 45gal drum (200 litres, I think), they will nest together and make a pretty tight seal and therefor a close to waterproof case that fits in that space.

From “Tim_Ha” on the TheSamba:

"12 Months on the road and 25k miles and this is one of my favorite mods. I have a swing out tire carrier so before the trip I threw this together. I picked up the 55 gal drum on Craigslist for $15. 30 minutes cutting it down with a saber saw and putting the latches and weather stripping in and called it good. Through all of the weather and mud and river crossings, not a drop of water has gotten in. “

> On Apr 1, 2021, at 7:00 PM, Bruce Todd <beeceetee@GMAIL.COM> wrote:
> 
> Maybe someone creative could build a tough round plastic insert with lid -
> you could have quite the water proof storage / tool chest below deck in the
> old clam shell - dedicated to all the stuff brought on the trip just in
> case - but still taking up much needed room regardless.
> 
> Still spare sparring here.
> 
> Bruce
> 
> 
> 
> On Thursday, April 1, 2021, Gene P <olgreywoof@gmail.com> wrote:
> 
>> You’re not missing anything Richard.  It’s a choice.  I like Ceviche with
>> shrimp, others want steak.  Nobody’s wrong.  One person’s contraption is
>> another person’s ingenious device.  One person’s hassle is another person’s
>> project.  Ain’t freedom grand?
>> 
>> From: Richard Koerner
>> Sent: Thursday, April 1, 2021 2:32 PM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Tire Holder?
>> 
>> I will submit a contrasting opinion.  I mean, what is wrong with a
>> standard Vanagon 14" steel wheel and tire put up into clamshell?  It's a
>> spare....just to get you to next town.  OK, I might understand it if you
>> guys are using big burly tires where the difference in rubber OD causes a
>> problem when getting to the next nearest tire shop.  For the many others of
>> us, say using GoWesty 16" alloys and tires which nearly match the original
>> OD and on a 2WD, this is not an issue.
>> Meanwhile, the trouble and expense of mounting a rear tire carrier?  Or
>> some contraption to accommodate big tires in clamshell?  After all,
>> rotating 4 tires is surely easier than trying to figure out the logistics
>> of rotating 5 tires.
>> What am I missing here?
>>