I have this one.
http://www.derekweaver.com/rodders-...weaver-w-898xs-tire-changer-assist-arm-combo/
I ordered it with out the power assist to save a few bucks, then last year I ordered the power assist after the machine made me some money.
My machine will do a 28" tire. The only down fall is on smaller rims. 13" need to be clamped on the outside, and some 15" aluminum also on the outside also.
And that really isn't a big deal, every once in awhile I forget to unclamp small tires before airing it up.
The air chuck end is a POS., so I added a short hose to run air nozzles and ect.
I keep track of the tires it has changed, I'm at about 300 in two years.
No issues with the machine at all.
Also I thought the company was top notch in every facet. When I ordered the power assist, they had my machine info on file. Apparently they had a design change, and made sure I was getting the correct assist arm for my machine.
I charge $15 for a dismount/mount. So the machine paid for itself in a years time.