The HF unibits are great in plastic. Tried them for tires without much luck. They tend to get hot instead of cut. Maybe the lubricant esshup talks about would help. Never tried that.

Tires will stay in place by themselves IF you have holes so no air being held. Out of the numerous ones I stacked had only one that floated to shore and had to drill some more holes and resink. I put rocks in a lot of mine just to be sure they stayed put and as a wedge to keep the sidewalls from colapsing on some of the flimsy ones.

John

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