Actually, those 245/45's are being stretched half an inch above max recommended. While I don't have much problem with running half an inch out of spec on the too-wide-wheel end, I wonder if that makes the tires more apt to follow road contours. Try to recall if the road had 'truck ruts' or similar out-of-flatness where you were fishtailing.
At this point, with traction problems but no hop, just relo brackets could help by increasing the anti-squat % (plants rear tires more quickly). If you can get your existing rear LCAs to fit up to somebody's relo brackets, try just that for starters. Not even LCAs yet.
'08 GT coupe, 5M, wheels, tires, pads, fluid, a few suspension mods . . . still almost stock height
'19 WRX, 6M (hers)
'01 Maxima 20AE, 5M (spare, winter driver)
Last edited by Norm Peterson; 01-10-2017 at 11:17 AM.
Reason: cleaned up wording/sentence fragment