Thank you all for most excellent replies, greatly appreciated!

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Tried linking a picture, original is several megs. To describe though, I get a puckering right at the wheel edge, from the fender seal pushing up the grip area. Would it hurt the front sensor to just trim 1/4" back from the wheel? There's a clear plastic sheet there!
I tried reversing and alternated tightening front, rear, diagonals, but always the same little slippage. Afraid rocks or debris will get under and cause the whole grip to come up. It is hot here, over 110 surface temp, usually. Just the heat?