For now, San Francisco 49ers offensive tackle Trent Williams doesn't know when he's going to retire, and he pretty much plans to keep playing until the wheels fall off.

Trent Williams, who missed the final seven games last season with heel and ankle injuries, is healthy, in shape and "right where he needs to be," according to head coach Kyle Shanahan.

Left tackle Trent Williams could make it into his 40s before he is ready to retire. As long as he's got gas left in the tank, he will be ready to suit up.