Tire load index
 

Just wondering but would it be okay to run a load index of 92 in the front if the rears are 97? I dont carry anything else in my car besides the wifey. Her and I are probably around 280lbs total.

Current wheel and tire specs:
20x9.5 255/35/20 97
20x11 305/25/20. 97

Have an extra set of the following:
255/30/20 92

I think you'll be fine.

http://www.tirerack.com/tires/tirete....jsp?techid=35

The tires will be able to carry a max load of 5,996 lbs.

Thats what I told the guy at American Tire but due to there regulations he said he cant Mount the tires.

That seems odd. You never want to force a shop into doing work they don't want to do but did he show you the regulation in writing? That seems like useful information.

I think static weight of the car is not as important as the weight + additional load the tires have to endure when you hit a pot hole/curb/bump. On a scale, my left front weights 972lbs, so around 945lbs without the tire itself. But rest assure, there's a lot more force acting on the tires when you run over obstacles, or during heavy braking, or cornering, or all at the same time.

I'm sure the oem load rating requirement has safety margin built-in. How much of that can you safely forgo? I don't know.