On Thursday, September 25, 2014 4:27:35 PM UTC-6, JS wrote:
Just finished this conversion.

Found a flat-free wheel and tire at the local Tractor Supply Co (tractorsupply dot com). SKU 3553230 "Never Flat Tire, 8 inch". It's rated for 220lb / 100kg and has a 2.50x4 tire. It's soft enough to provide some shock absorption.

But that wheel has 5/8" bearings, and the bearings are offset to one side for installation on the end of an axle.

That can be fixed with two 1/2" ID, 5/8" OD brass bushings (the ones I found were 1 1/4" long) and a third brass bushing 5/8" ID, 1" long as a spacer to the other side of the caster fork. Your caster may require a 1/2" flat washer on the opposite side to the bushing. All available from True Value Hardware, bushings $2.40 each. A 3" brass bushing from McMaster-Carr is a better way to go but $10.50. Another method, 1/2" bearings to replace the 5/8" in the wheel are about $4.00 each, still requiring a 1" spacer.

_ My total cost was about $23.00.

It's "hecho en chine" but haven't found a domestic 2.50x4 "flat free" yet.. Anything wider won't fit the standard tail dolly casters. If anyone finds a more appropriate wheel, please inform.

Jim

Hospital gurney wheel from eBay ~ $10. 10" forged aluminum disk wheel, airless soft urethane 'tire' and incredibly smooth, free running bearings. Fits tail dolly perfectly. Only downside is it's slightly heavier than the OEM wheel.