I think this is what your asking for, I may be misunderstanding the question. The red line would be the top of your OE fender. If you are running 40s then I would assume you are running full width or wider axles. This should make it harder to contact the inner fenders, when turned to full lock you also have the radius of the tire falling away from the inner fender.
"I'm finding that even with a 1.5"-2" forward stretch, 40's still hit the inner fenders" @sierradmax Please post a pic if you have it or show where you are seeing interference with 40s. I put a 40 inch circle with dims from tub to center line if that helps. Are you seeing contact at the bottom area close to the rocker?
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This is of course not turned, just seemed easier to compare dims in this orientation.
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With fodeez, the clearance issue becomes the rear of the inner fender at full stuff and full turn. I think that is what Sierra is referencing..
