I seen the thread an had to chime in, Tim and the guys over at Piston Driven are friends of mine so I asked Tim about the OCIR question here's his response:
"it is not always the intent to make every shirt or design period correct.
the fact that OCIR had an indy type car on it was not really in the spirit of drag racing. they thought they would have many types of racing and never did. just drag racing.
so we are about more than just printing another copy of a race track name or logo.
more detailed embellishment, high quality 100% american made cotton."
Check out all of there designs including some really cool Car Craft and SEMA shirts. the web site is
Piston Driven : Vintage Motorsport Apparel and Signs
-Don