Mountaineering Boots Insulated mountaineering boots with completely rigid soles are needed to climb Mt. Rainier. While both leather and plastic boots will work well, each has strengths and weaknesses. Plastic boots will work well all season long and are particularly useful for climbers with colder feet and climbs scheduled in early/late season (mid May - June and September). Plastic boots require no break in period. Appropriate leather boots (stiff-soled, insulated and designed to hold a crampon) are appropriate for mid season (July/August) and warmer weather climbs. Whether leather or plastic, mountaineering boots are designed to remain stiff for kicking steps and working with crampons. To ensure that your feet do well, mountaineering boots must be comfortable right from the start. If renting boots, consider bringing personal orthotics or footbeds.\\\\\\\\r\\\\\\\\n\\\\\\\\r\\\\\\\\nThe two most important factors when purchasing a boot are 1) it\\\\\\\\\\\\\\\'s intended use (where will you be climbing) and 2) ensuring a proper fit.