Rocket-Sauce 

Forgive me if this has been covered before. My attempts at using the search function have been fruitless.

I am considering getting my daughter a road bike that comes with 650c wheels with 650c x 23mm tires. I'd like to put on some fatter tires since she still rides kind of rough (she is 8yo). Will 26" mtb tires work? Looking at Sheldon Brown's site, they both are 571mm. I am just hoping to find something wider than 650c x 23, preferably 650c x 28 or fatter. Can't get too fat, because the brakes will not clear. I am thinking 32s will be the widest. That would be 26 x 1.25, right?

Thanks!