So I've seen a few super low mile IROC's lately that have the factory 15" wheels. So I got to thinking..the 16" wheel IROC's have a different steering box than any other 15" wheel cars. The 15" wheel cars have a tighter turning radius. So are 15" wheel IROC's the same way? Did they get the RS and sport coupe steering box?

 

I had one of those for a very short time & I just might have a picture of the SPID decal if that tells anything at all? Funny, I was just last week talking about those wheels on the Irocs with a friend of mine. I still remember driving past the local Chevy dealer in 1989 & seeing one parked out front & instantly knew something looking amiss.

Was told later that not everyone liked the harsh ride, but wanted the Iroc look. Any truth to that? Why did they make that change / option?

 

It probably had to do with both cost and marketing and to a smaller degree, ride quality. In 1987, you could get the Z28 with 15" wheels or the IROC with 16" wheels (and the upgraded suspension). In 1988, they were all Irocs, so the the 15" wheel Irocs took the place of the Z28 from the previous year. I'm sure it had a lot to do with marketing/pricing to offer an Iroc for Z28 money. Back then, there was much more desire for Irocs over Z28's.

 

The 1987 Camaro brochure shows the following:

 

Thank you! That answers my question!

 

It's always been my understanding that the 15" wheel Z28 box and the 16" wheel Iroc-z box was the very same unit. The ONLY difference was the internal steering stops in the boxes were tuned for each wheel size.

Also it's worth noting, the base Iroc-z in '88 used the old 15" Z28 wheel, as the standard Z28 model had been discontinued. The "smaller" 15x7 Iroc-z wheel didn't come along until the '89 model year.