Sorry but I'm not a big fan of tire widths and sizes, but since you are, okay. Also, I wouldn't be so confident in Forza 5 though, it looks to be the same FM4 with better graphics and drivatar (even with open-wheels), but that's my opinion. It has no night racing, no weather, and even no pit strategy AGAIN, but it was already said by Dan he doesn't care what the fans say, he believes his game is better than PC sims and all racing games anyway...
The reason I'm excited for GT6 is mostly for its updated course maker (something that I love in racing games).