Are you sure they weren't Dakota M/T?
http://zukiworld.com/forum/index.php?topic=20578.0There's a HUGE difference between 29" and 31" tires in:
* Ride quality
* Rolling resistance over obsticles
* Gas mileage
* Power
* Slow crawl speed
* Suspension & backspacing needs
* Survivability of drivetrain
* Emergency breaking distances
Think about the terrain you'll be going over, how often, and how hardcore you want to get. These variables will dictate tire size, tread pattern, construction & compound - which dictates everything else (suspension etc). I'm a HUGE advocate of 29" tires & locker in the diff(s). But, that's just me
With 29" tires, you may not need a lift at all - with 31" go with spring spacer kit (Jeff's kit has had good reviews, and is unbeatable in price...)