this is too small for a rat, rats are a lot more Intelligent then hamsters and need mental stimulation, they need big cages and should have 2 cubic feet PER rat. they need multiple levels and lots of toys.
You shouldn't use pine or ceder shavings either as they are toxic to ALL small rodents such as Rats, hamsters, mice, gerbils and so on.
you need to buy a cage that is made for a rat or a ferret. Also rats are much more social then hamsters and need friends, you should get a same sex friend for your rat.
rat owner, http://www.rattycorner.com/odds/calc.shtml
and information i have gathered from verious websites and people.