Hi, I am researching all of the PPG Pace cars and came across this forum while looking for any info on the 1989 Turbo Grand Prix. I was also the guy who owned the yellow wheels posted above - small world huh?
Let's start with those... They are 16" BBS RSII wheels, custom painted. The tires were Goodyear Eagle VR50 with shaved tread. As far as I know, PPG kept more than one set of mounted wheels/tires on hand for each pace car. I purchased a few sets of wheels from the auction they had at their warehouse in Strongsville, OH. I know for sure one of the Mustang's wheels I purchased is in Jack Roush's museum with another set of the same custom wheels. So the Pontiac may be alive and well, despite these wheels being sold separately. I put the yellow BBS on a 1994 GTP but ended up selling them. (20 years later, I wish I hadn't now.)
My dad worked for PPG, so I got to go to some Indy races as a kid/young teenager and see many of the PPG Pace Cars in person. I've always had an interest in the Pace Cars and have been gathering images of them over the last decade. There's about 100 different pace cars! I don't have any additional information on the 1989 Grand Prix, but do have one photo that you guys haven't posted.
I'm in the process of adding this car to an online catalog of all PPG Pace Cars that I finally got around to starting this winter, http://ppgpacecars.com/
I originally thought that most cars were destroyed, but while building this site I found that quite a few made it into the hands of private collectors. There are also a good amount in museums. Only a small portion have been confirmed to have been destroyed.... so there's hope for the Pontiac.