Looking at the Indy version of GL's I noticed the winged tire Indy 500 logo is missing from the sidewalls. It looks so cool in real life I was half tempted in the pits at Indy to try and walk off with one as the ultimate souvenier but I came to my senses when I realized there was no chance of me getting away with it or out running anyone. It's not like the logo can't be done as I see it all over the cars themselves in fact that same logo is on the street version tire as well and could look pretty cool on a street car too.

Maybe it comes down to license fees? Always money getting in the way?

Yep, that's the same thing that happened in model kits - the tire companies wanted licensing fees for using the correct text/logos, so most manufacturers are opting for bare sidewalls.