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
Last edited by RonD; 04-04-2015 at 10:59 AM.