Have you tried taking the car up to that rpm in another gear to rule out something in the drivetrain? Other than that, borrowing a set of wheels is the only thing I can think of. Though the rotation kinda ruled that out, unless there is something wonky in the axle/hubs.
J
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'66 Mustang Coupe- AKA "Lenore" *on disability for a (long) bit*
'93 GT Mostly stock AKA "Fawkes"
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