I want to go to 305/7or16 tires I am currently running 285/75r16 with the stock gears, can I get anyway with running the 305 with the stock gears or will I have to change them out, if I have to change them out what kind of gears will I have to get installed thanks

 

You can certainly run that size with stock gears. Won't hurt anything. You may notice a drop in perceived power, as well as a drop in MPG. But you can run that way if you want.

 

x2. If you are already comfortable with running 285/75s w/ stock gearing, then 305/70s are not going to make a big difference...in fact, it will be minimal at best. The 305/70 is very similar to the 285/75 in overall size.

Personally, I'd regear with 285/75s, but that is just me.

You can compare both tire sizes here: http://www.wickedbodies.net/Tire-Size-Calculator.htm.

Granted, which ever brand of tire you decide on, you may want to get the exact dimensions from the manufacturer of each. Reason being, every 305/70 for example, is not exactly the same size as another.

 

If I was to run the stock gears how much would it hurt power and gas

 

I would assume, just as much as the 285s do now + a little more. Again, the sidewall height, tire height and tire circumference is almost the exact same between both tires (by comparing them to the website I listed above). It's the section width that becomes greater. It goes from 11.22 to 12.01 inches. Therefore, it's not a huge jump up in tire sizes. You should see a decrease in mpgs and pwr, but I do not foresee either of them greatly decreasing from what you are already experiencing.

EDIT: Exactly how much would it hurt pwr & mpg, I can't say. You want know exact figures until you do the swap. Wish I could be of more help

 

Stock gears with black steelies and 35's = loss of acceleration and braking. MPG is about 18+ on hwy and 15 in town.

 

lots of gears came stock what do you have in your truck?

http://intercotire.com/site63.php

 

305's and 285's are basically the same height. the 305's being just slightly wider...so you should barely notice a difference if any at all...