On my two seater I made, I used junky hand cart rims, so I know this from great personal experience. NO GOOD!
I had to replace all the bearings in short order, and the tires shortly behind that. If you want a 4" rim, they might be useful if you know you'll be replacing everything. But I think you should get the good ones from the get-go. I put up a new thread discussing wheels and tires in "hardware" section.