In most cases it seems about a 2" difference front to back is ideal, but it really depends on the wheel diameter and face/spoke design. Also the lower the ride height the deeper the lip can go and look good. Deep lips at stockish ride height, even with the right offset looks terrible IMHO.
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1965 Ford Falcon Hardtop - PT Build
TCI Supension | Team III Wheels | Ford 3v 4.6 & TR3650
Everyone is going to have a different opinion, this is purely a personal decision. For example, I hate 20" and bigger wheels but that is just my personal preference.
__________________ Steve Hayes
"Dust Off"
68 Camaro
Speed has never killed anyone. Suddenly becoming stationary, that's what gets you! "Jeremy Clarkson"