Speaker sizes and available adapters

I have a 2011 Aveo5 and I wanted to replace the speakers. All the sites I go on to order them from are all over the place on what sizes will fit. I have a pair of 5.25 Pioneers I pulled from my last car to install just to find they were a little bit too big to fit into the stock plastic riser on the door. So I find sites stating 4" speakers are what go in the front door, but to me it doesn't look like there is a 1.25 inch difference between the stock speaker and my 5.25's. I'm not an expert on how those speakers are measured though. So anyone know what size speakers this car takes, and also I know people are swapping them out so there has to be adapters out there which I can't find.....

Aveo's have 4 inch speakers. Get an adapter ring from a local audio store(no, not best buy) or make one your own, out of MDF. G'luck!