I just went out to my truck and took pictures of my RPO code sticker inside the glove box and the door sticker inside the driver's door. I saved them to computer for my own record keeping and then found a 188-page document that translates all GM RPO codes. I found a discrepancy between mine. There are four RPO codes on my truck that all say my truck came with 235/65-16 tires. My OE tires were replaced long ago but I want to say they were 245/65-16s. I just replaced the spare this past December and I do remember that being a 235. The odd thing is, the sticker inside the driver's door (that also recommends the air pressure) says right on it "245/65-16". So, why the difference between the RPO codes and the door sticker? Which one is correct and is it common for them be different?