Hey gphil. I know this is not what you are looking for, but it may come in handy in the future. I wanted to go to larger dia. tires on my Nexstar. Being a trike, the two mainwheels were no problem, just bought larger dia. axles. The nose wheel was a different story until I came across these from Robert. Cut the vertical part of the 5/32 wire axle off and on goes one of these, bingo, 3/16 axle.

http://www.robart.com/products/532-w...apter-316-axle