Used tires are the most crucial component of Earthship construction.
Tires are pounded full of dirt to create rammed-earth blocks. Building the massive retaining wall of tires is the first phase of construction. Work on the tire wall starts after the ground is leveled and the layout has been marked out with string lines as described in this video Tire layout.
The tire layout is shown here in this floor plan.
The tires must be gathered from various sources and stored onsite before the build starts. Automotive shops often will have large quantities of used tires that they haven’t taken to the dump. Since they have to pay loads of money to have them disposed of, automotive shops will often just give them to you (if they are really grateful for the cost savings, they might even deliver them).
How many tires are needed?
Hundreds to thousands. The exact number depends on the outside dimensions of the Earthship. Larger spaces require more tires. Smaller spaces use less.
Here’s how I estimated the number of tires we will need for our 1400 sq. ft. home:
Our home footprint will be 20 ft deep x 70 ft long. The total length of the tire wall includes two (2) tapered ends, two (2) side walls and the back wall. (I estimated the tapered ends to be 10′ each). That’s 20′ for the ends, 40′ for the side walls and 70′ for the back or 150′ total. 150′ x 12″= 1,80o ft. Divide that by the standard 15″ tire diameter to get 120 tires per layer (also called a course). There are 10 courses total.
That is 1,200 tires for a 1,400 sq ft home.
Which tires are best?
First, we need to discuss some tire numbers. Reading tire sizes
The tire’s sidewall will be printed with a size in this format:
The numbers we are most interested in are shown in RED
The first number is the tire width (millimeters) from tire from sidewall to sidewall.
The second number is the wheel diameter (inches) from tread to tread across the center of the circle.
A tire wall starts with larger tires at the bottom and ends with smaller ones on top.
The tires also need to be completely intact or else they will burst when pounded.
We need sizes: 205/15 215/15 225/ 15 235/15 235/16