If you have the vehicle....and no one has peeled it off or painted over it..(I hate that!) on either the edge of the door or the door jamb at the striker end there is supposed to be a sticker that lists the OEM recommended size tire for this vehicle at the time of manufacture.
Also....as the above thread indicates....usually inside of your glove box or center console door there is a GM sticker with a bunch of gobble-dee-goop printed....all letter and number codes. Any competent GM parts person ( is that an oxymoron or what?!?) can tell you more about your vehicle by identifying these codes.
If neither is available, the same parts person can de-code your VIN and print out for you this "code sheet"...then it will tell you a lot, such as alt amp output, H.D. Cooling, gear ratios, and all kinda usefull stuff. I usta have a little book from GM that told me all that stuff....now if I can only find it in all my junk!
Steve
