According to this link below, the SSIII Rallye wheels for 1978-1988, had a 3.5 inch backspace for the 14 inch size.

http://www.442.com/oldsfaq/ofwhl.htm


I am looking to replace my 14 inch steel wheels with Olds SSIII Rallye 15X7 with 4.25, but is that backspace too much?

I am going to put on a 205/65/15 tire on my 78 Cutlass.

Thanks for the replies. I like to place an order with Blue Oval as soon as possible.

 

This is why I like to use offset instead of backspacing. Backspacing is affected by wheel width, so you can't compare backspacing of wheels that have two different widths. Offset is the absolute dimension from the wheel mounting surface to the centerline of the wheel.

In this case, the 3.5" backspace is for a 6" wide wheel, the 4" offset for a 7" wide wheel. They are roughly equivalent as far as offset is concerned.

 

Joe,

Thanks for the quick reply. Much appreciated as this eases my mind since this car came with steel wheels and hubcaps.

 

I would measure closely on the rear. Depending on the tire bulge it will be close to rubbing the frame.