What kind of pork ribs? Spare ribs, St Louis cut, babybacks or something else?
I love to salt & pepper, cover with a light coat of yellow mustard and press on about 3/4 of a cup dark brown sugar on St Louis or spare ribs. I them slow roast at 200 degrees in the oven for at least 2 hours, longer if I can and finish them on the grill.
If you can set your grill that low, I don't see any reason why you can't roast them out there. Are you using a gas or charcoal grill?
I like the ribs finished at a higher temperature on the grill to get a nice crust, which is easy for me with the gas grill.