Collidescope Cornwall

So we are now o to the next smaller size of tires for our tire wall and we have done a dry stack and the tires start off one inbetween the two below it but by the middle of the wall they are now one tire exactly above the one below it and by the end of the wall they are back to lining up one tire above the two below it.

Is this okay? We dont want to ha e to use spacers, so how else is this done when moving to the next smaller size of tires.

We are building a half cordwood and half rammed earth tire wall round building. The rammed earth tires will be acting as a retaining wall as that half of the building will be in a large bank. The other half of the building outside the bank will be a 2foot thick cordwood wall. We are at 3200 feet elevation in Canada BC so our cordwood walls will hace a 3.5 ft deep rubble trench foundation but ive read everywhere a tire wall doesnt need a foundation. should we make the rubble trench all the way around the building, or just under the cordwood part that is outside of the bank? It seems that having just half a foundation would be flawed but i cant find any info regarding what to do in this situation. In earthship builidng does the framed walles have a foundation but the tire walls do not? how does this work? Please and thankyou.