Check out Diamond Gussett jeans. They make just about any size you can imagine. They are 100% made in the USA, and the company is a joy to deal with.
I drive a truck (locally) for a living, and my motorcycle is my primary means of transportation. No other pants are as comfortable for driving, riding, or just sitting on a barstool. They are high quality, and last a long time.
They also make jeans designed for motorcycle riding with kevlar in the knees, hips, etc.
(Maybe Levi's should start putting kevlar in the knees of THEIR jeans.... for different reasons, of course!)