Service manual says alignment specs are for "unladen" conditions... meaning fuel and coolant are full. They even go so far to say even the spare tire, jack, hand tools and floor mats are supposed to be in designated positions.

I've read lots of alignment threads on many sites.. but never saw comments about making sure you have a full tank of gas. Would the weight difference affect the numbers much?

 

i belive that the aligment specs are set to account for the above.

 

I don't think it would be a huge difference, but why not just fill it up before taking it in just to make sure? I just installed shorter springs in the rear of my car and I can tell a difference in the wheel gap between when the tank was empty and after I filled it up.