Many years ago, I had 6 inch widened steel wheels on my '73 144, however when the shop welded the standard 5 inch centres into the 6 inch rims, I asked them to maintain the existing offset. This had the effect of adding 0.5 inches both ways. They were fitted with 205/60 15 Yohohama A008R tyres. There were no ill effects on the front, although at the rear, it was necessary the roll back the 0.75 inch lip on the inner rear wheel arch to prevent the outer edge of the rear tyres rubbing on that lip when the suspension was in bump.