Yeah.... I have an early Slash, which has 2.2 wheels on it, inside and out. The newer ones have the same tires and wheels as the Slayer and look identical to the ones I have on the ousides.
Slash and Slayer have totally different chassis and suspensions, although they sit and look pretty close to being the same: a 1/10 scale CORR truck.
Now.....I just ordered/received all new STOCK wheels for my Slash through Tower Hobbies, and the Slash has changed over to the funky wheels used for the Slayer..... and you can only use stock tires on them, due to the size difference. I've seen them on newer Slashes in the hobby shops. I just got them, and all for nothing....
You could probably swap on a set of tires and wheels from a Revo on the Slayer, but.......