Hiya folks, I have a 2004 Jeep Wrangler X, 4.0 I6 5spd MT. It's my first jeep/truck/utility vehicle. I bought it used and it came with 31" Cooper A/T tires. I'm wondering if I need to or if I would benefit from regearing? The Jeep feels super sluggish and I can barely hold 55mph going up Donner...