Being new to mountain biking I still have a lot to learn. Take tire sizes for instance - it there an optimal. I'm currently running 26" X 2.1 on my Klein but have some 2.35 Klein Death Grips I could use also. Is there that much of a difference? Better grip on which ones? What are the benefits to wider vs. narrow from an mtb perspective? Some of the guys on our 24 hr race team this last weekend were running 2.0's which to me didn't look that much different from a width perspective. I even heard of someone this past weekend running a narrower rear tire in the race than in the front.