Woo. Old thread. Sorry about the photos being gone, but that's Photobucket.
Sure, you could ride it on 25's, not the ideal thing, but I'm sure it's been done. It's not like you're going to bog down anywhere.
I'm pretty sure there is a fee- it's just the park entrance fee, I think- call and ask if it's critical.
There's a Caprock Canyons rail trail out between South Plains and Estelline, and I'm planning to do it in late April.
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"be careful this rando stuff is addictive and dan's the 'pusher'."