When I compare them the hub on the fronts is smaller. Does anyone know if the 10.3 front rotors will fit on the rear hubs?

 

No they won't because the hat's height offset isn't the same neither is the thickness of the rotor as well.

But, there are factory rear 10.3" rotors found on the 02-04 EP civic Si that are compatible with 4x100 honda's. Only thing, is you need to get the right caliper to use these rotors.

ITR or CRV rear calipers are key to use. You can get away with EP/DC5 rear calipers as well, but they don't mount the hand brake cable very cleanly like ITR or CRV calipers would.

 

Katman is correct. 02-04 ep3 rears are 10.2". Cost about $13/ea. Fit right on as they are 4x100.

On a side note. I have a set of ep3/rsx rear calipers with the correct hardware to mount up the stock e-brake cable. They are for sale.

I also have a set of ITR rear calipers for sale. Pm if interested.

 

If using nsx rear calipers, then I believe you need the thicker vented rotors. However I'd advise against nsx rears. Thats way too much rear brake one a civic/integra.