Interesting, my experience with Levi's and Wrangler is equally the opposite, and to the larger extent - 501's, 510's would barely survive 6-9 months of wearing, while Wranglers (mostly Arizona And Texas) happily roll into... <checks purchase date> third year.
Washing in 30 degrees, always tumble drying on low (dryer has a humidity sensor and stops when it's dry, doesn't overdo).
Levis quality has gone done and their pants doesn't last long, but neither does most Wrangler. However, Wrangler does have a line of pants made from 100% cotton, not added elastic materials. I have yet to test, but my theory is that the people who have long lasting Wrangler may have purchased the 100% cotton variant, but remind unaware of that fact.
Washing in 30 degrees, always tumble drying on low (dryer has a humidity sensor and stops when it's dry, doesn't overdo).