I was just curious what others on here running 20 or 22 inch wheels have done to make them fit their Riviera boat tails. I am curious about the backspace also on the wheel.
There are no back space requirement differences between a 15" wheel and larger wheels. Wheel width will affect the back space requirement though. Look at the Rallye wheel chart, http://www.v8buick.com/index.php?threads/official-guide-to-rally-wheels-chart.196455/ The big car wheels for 71-85 (5 X 5) were 6" wide with a back space of 3 7/8". If you want to keep the tire centered in the wheel well, then for each 1" you widen the wheel, you add 1/2" of back spacing. So for a 7" wide wheel, you want 4 3/8". For an 8" wide wheel, 4 7/8". You can also measure the back spacing on your current wheels and go from there.
