Just wondering if i went from the stock 18 inch tires to the BFG 285/65/20, do I have to be concerned with braking issues or power loss.

 

Yes - for every 10 lbs increase in unsprung mass you will loose ~0.1 sec in the 1/4 mile. Of greater concern is the decrease in braking efficiency. You can excpect to add ~10 feet to your 60-0 breaking distance for every 10 lbs increase. With 285/65/20 I expect you are going to add about 40 lbs.

To support my case, Dodge will not upgrade a RAM with stock tires to the option 20s at the dealership. This must be done through the factory - Why? So the factory can supply a numerically higher rear end to compensate for the lose in acceleration.

 

Not only the obvious weight penalties, but the longer radius of the tire decreases the braking effectiveness. Baer makes a larger brake rotor for 04-08 trucks to help counteract the larger tire issue. It comes with revised bracket for the brake caliper. Check out their Eradispeed plus offering. The power loss will be more of a gearing issue. While you have more rolling resistance, the gearing aspect for power will be off. Gearing will not get all your performance back, but it'll be as good as it gets. Since many of the PCM functions are based on proper input, you need to either get a programmer or find a way to recalibrate your PCM for the correct tire and VSS inputs.