If you don't mind the shipping
DG Defender
Diamond Gusset Defender Jeans are really good they are a heavy denium with kevlar in the knees and around the seat/hips/crotch, they have a velcro strap at the bottom of the leg to close off air/keep on the boot, they are not vanity sized meaning you can measure then order true to fit size with a huge selection of sizez and combinations and its a small company so if you email or call them they will work their asses off to help you. Plus they are from Bon Aqua TN so got to promote some Volunteer state products!
Stryke Motor Pants (not really jeans but damn nice for cost)
Another one like for hot weather is 5.11 Stryke Motor pants. they are made of Flex tec ripstop fabric and have kevlar in the knee and seat / hips. they also have elastic stirrups for keeping the pant legs down. their sizing is traditional retail and the inseam stops at 34". which are a hair short for me but doable. unfortunately they are limited due to being closed out but are on Sale for $50 USD through 5.11 tacticals website. through amazon they are over $100 USD.
both have really good thick kevlar. are comfortable and i have thousands of miles in both.
my nartual waist is 36.5" and inseam is 35.75" i am 6'4" tall at 265lbs. Defender jeans 37" waist x 36" inseam (long for winter layering) Stryke Motor Pants 38" waist x 34" inseam