22mm internal is fine, it allow you to drop the pressure and thus create more room, however you can go to 17mm internal and still be fine (that what I usually run on my 650b bikes) the difference between 17mm and 22mm internal is very hard to tell when the tyres is that big.
toight! Should be fun to ride though. Have you got a caliper to check the actual tyre width? They are 19mm internal rim yeah?