The biggest thing I have found, rusty or not, is that you need to push straight down on the bead. Not the sidewall, and not against the can of the rim. You will literally be beating your head against the wall doing it this way.
Since there is no indent in the can of the rim, the tire needs to go straight down. Using the tire hammer, I find that once you move the bead down about 1/2 inch or so, then you can use a hi-lift and the truck to move around the bead and push it down. The key, is getting the base of the hi-lift onto the actual bead and not the sidewall, where it will just slide off, or push ineffectively against the tire carcass.
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