I've got a 2002 XLT 2WD

Its has a 3 inch performance accessories body lift

At the shop we just started getting a new brand of tires called Hercules, which seem to be holding up pretty well.

Curretly I am running a 265/65/R17 tire on 17x9.5 wheels, the tire I want are the Iron Man All countries....
The only size that will fit a 9.5 is a 315/70/17.

Personally I think they gonna just barley squeeze on there but would like to get some opinions...

Thanks in Advance!

 

You would be going from a 30.5" tire to a 34.5" tire size.
Rear probably wouldn't be an issue
Front would rub and limit turning radius

And assuming a 3.73 rear axle ratio the 34" tire would change that to a 3.25 ratio so you would notice a decrease in low-end power/acceleration from stopped.
You would probably want to switch to a 4.56 rear ratio, that would put you at a 4.00 ratio

3.45 ratio is for better MPG at highway speeds, but sacrifices a bit of acceleration and towing power
3.73 ratio is the mid-line, OK for MPG and OK for towing but not great for either
4.10 ratio is best for acceleration and towing but has a bit less MPG at highway speeds

There are also specific use ratios
3.08 would be strictly for highway MPG, would be hard to get going with a trailer or much of a load in the bed
4.88 good for acceleration and towing, engine would be at high RPMs even in OD at 70MPH so MPG would take a hit.

Changing tire size changes the mechanical ratio because a 34" tire rolls farther in one revolution than a 30" tire