Time to think about upgrading your mountain pants. As the snow piles up around Lake Tahoe and elsewhere, no average pair will do. You need something with a little more heft, with reinforcements in key spots (to protect you when you put those dang chains on or muck through those thigh-high drifts) and a little extra give. A number of manufacturers delivers some high-test pants that work well in winter and fall, heavy weight fabrics, double and triple stitching, gussets and a whole lot more features set them apart from their run-of-the-mill counterparts. We tried a few from Duluth Trading, Kuhl and Mountain Khakis. Here’s what we learned.