Tires: car tires, bolt circle, saab 900s

Question
I have recently bought a 2001 VW Beelte and it came with tires that are going to need to be replaced by Sept. 2010, and I have a 1991 Saab 900S with just about brand new tires on it, but the transmission needs to be replaced, so I was wondering if I could take size 185/65 R15 and put them on 205/55 R16?

Answer
Nicole,

First, the tires from the Saab are 15" tires and they will only fit on 15" rims.  Your VW has 16" rims.

Second, the rims won't interchange because the Saab has a 4 X 108mm bolt circle and the VW has a 5 X 100mm bolt circle.

There are some other reasons why this change won't work, but the above is sufficient.