I had the Nitto 420S as well in that configuration. 255 55 18. Loved them. Would do great in SoCal. They were fine in the wet, but be cautious in the snow. Those tires looked amazing and gripped quite well in the twisties. You should be able to pick up a set for under $600. I will probably buy another set this spring and run them as my summer set.

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2005 X5 3.0, 6MT, Alpine White on Truffle Brown, Sport, Preim, and Cold Weather, Alpina Stainless Headers, AFe Intake, UUC SSK, OEM 87's, 3.64 Differential Swap,Performance Modified Euro 2 Tune, UUC LTW Flywheel and HD clutch, Bilstein B12 Suspension kit
Future mods ZHP/Schrick Cam Shaft upgrade, Operation code name:Doppelschrauben-Kompressor

Wife's Ride: 2011 e70 X5 351 M///Sport.

Also in the fold: 2004 X3 3.0, 6MT, Black Sapphire on Terracotta, port, Premium, Cold Weather.