285's or 265's???

you will go down on the mileage.
1. rolling resistance: your bigger tires need more power (fuel) to turn one revolution (the are wider and have a larger circumfrence)
2. the small height increase, although you don't notice it, puts you higher in the air and makes your horrible aerodynamics slightly worse.

You will almost always get your best mpg with the size tires that the vehicle calls for. the manufacturer tuned the car for those size tires.

 

All right, got the spacers on today at work. Turned out pretty good, and about as easy to do as taking off the wheels. Completely eliminated any rubbing I had, although I may have to trim the fender liner a little bit at the rear, as it looks like it might rub a little when the suspension compresses in a turn.

I did however, gain a bunch of room between the UCA, and the tire. As you can see in the pics, hitting the UCA won't be a problem, now.

I have pics of the suspension clearance at full droop, too, if anybody wants to see 'em.

Before the spacers


After the spacers


Clearance before spacers, truck on ground


Clearance after spacers, on ground

 

Bigger tires are a great excuse to get a lower gear ratio! I'm already looking at going to a 4.88!!

 

i thought 285s are too wide for the 7" wide oem wheels. guess i was wrong.

 

per most manufacturers, it is, but anything can be done...

 

with 33s? you will be spinning and burnin up tires...

4.56 is a happy medium...

 

My OE wheels measured 7.5" with our calipers for the balancer.

 

I'll decide after I drive a truck with both. Our terrain out here is very hilly, and at freeway speeds (~75 mph) I'm constantly going in and out of OD with my bed loaded down. That was even with the 265's on it.

I also see you have excellent taste in trucks!

 

Looks great man! Does it ride any different? I just got my bilsteins and shackles on today, next step is tires and spacers.

 

Still rides nice like it did before the spacers. I did notice it wandered a little at intersections, but you kind of have to expect that with the widened stance.