had a customer come in today w/ an 04' scab fx4 4x4 build date was 06/03..
i could not believe how much lower his stood then mine, i did notice he had 17's w/ the generals for tires....does going from a 17 to an 18" make that big of a difference? his truck had the stance of what a typical 1500 sliverado does...

 

The 18's do make the truck sit a little higher.

 

Aren't the General tires a 245?

My stock tires are 31.9 Inches tall. (I have the 18's)

This must make the difference that you are seeing. Larger tires give some decent increase in ride height.

When I go from my 33X13 Toyos to my stock tires, my truck feel Tiny!

 

Another thing to consider is that a lot of people have recorded different stock heights with the same configurations.

 

They are a 255.