Preparation of tyres for use as planters, and their sizes and volumes

Only now, after nearly 100 deployed tyres, do I learn what I should have been doing all along, which is this:

To reach this stage, you need the right tool for the job, which, according to an informative Youtube video, is:

Cutting the sidewall out of the tyre using a hook blade in a box cutter is actually trivial - it takes a minute or two, even for very large tyres, but requires a bit of pressure. You just have to be careful the knife doesn't jump out and take a chunk out of your shin when you're pulling on it.

Initially, I was concerned about reinforcing wire in the tyres, but the Youtube video showed there aren't any in the sidewall. So, getting carried away, I sorted out the days collection of eight new tyres (which means I've now reached my space limit - unless...):

Normal tyres, destined to contain more piquant peppers.

Two larger 4x4 type tyres, destined for bigger, more perennial plants - perhaps ultimately horseradish/globe artichokes? Or Patty pan squash? The other two large tyres contain a transplanted rhubarb, and some red skinned potatoes.

Then I tried my hand at dealing with some of the existing tyres, and it was an easy enough cut even though a bit awkward to manoeuvre round. Say three minutes instead of two. You'll notice the improved technique giving a more regular cut closer to the treads. The weight of the filled tyre gives a bit more control while cutting. An empty one moves around quite a bit under the pressure of the cut.

You can see the extra surface area for planting that can be obtained by taking out the sidewall from the impression of where the rim was. I'll do some measurements and calculate areas and volumes tomorrow.

And you can see the effect of the rim on water penetration - the rim acts like a roof, so only the middle part gets direct moisture. Also it's a haven for slugs and other beasties.

The down side of removing the sidewall from a tyre already filled with compost is that there's nowhere to hide the detached rim, which could be a bit of a disposal problem. With a new tyre it's easy, you just put the separated rim into the bottom of the empty tyre and fill it up. It's guaranteed to fit in there quite neatly and takes up minimal volume.

Now it's just a matter of slowly sorting out the un-modified tyres as I replant over the next several months/years.

Should have done this ages ago, but it's never too late to learn. I'll need to adjust the irrigation system to cover the new additions.

Update 2015/11/14:

Here's the numbers for 1 medium size tyre:

Diameter across trimmed sidewall = 520mm. Radius = 0.26m.

Diameter with sidewall = 400mm. Radius = 0.2m.

Depth/height = 200mm, = 0.2m

Some arithmetic: Surface area with sidewall = 0.126m^2, circumference = 1.126m
                                             without sidewall = 0.212M^2, circumference = 1.63m

So, cutting out the sidewall increases the surface area by 68%.

Volume without sidewall = 42.5 litres.

Weight of compost (density 590kg/m^3 according to superficial google search) = 25kg.

Here's dimensions and associated numbers for other tyres:

Wide rim height = 300mm, radius about 280mm, Volume = 73 litres. Weight of compost = 43kg.

The 4x4 type tyre.

Diameter = 650mm, radius = 325mm (average across distorted oval shape).

Height = 260mm.

Volume = 86 litres. Weight of compost = 50kg.

Now I have a total of 103 average size tyres installed, and 4 large, so total weight of compost required was = 2775kg, or 2.8 metric tons. Just as well that I make my own!

That's a lot of leaves and stuff.