"Pickup only" is going to limit the prospects of getting these to a good home.
I can understand why you might decide on pickup only, as it can be a royal pain to find a box and packing materials, pack up the wheels, take the package around to various shipping agencies for pricing, then work with the recipient to get reimbursed for the cost of shipping.
But the process is not that bad. For the box, I'd go to a local
UHaul and pick up one of their "sport utility" boxes, $5.95 plus tax. Then you'll need a utility knife and a couple of smaller boxes (Amazon boxes are everywhere) that you can cut up. Tape the bottom end, stand it up, and put each wheel in one at a time like you were filling up a roll of Lifesavers. When shipping wheels, the most important thing is to keep them from clanging together, so use the cut up cardboard as a divider between each wheel. You'll want to snug the rims of the wheels against the side of the box, so anything soft and light will do, like an old pool noodle. You can also use folded cardboard. The biggest void is going to be at the top you're going to have about a 10" tall empty space, but an empty cardboard box will fill that just fine.
Don't worry about using too much packing and stuffing thereby increasing the weight, for a box this size you are well into "dimensional weight" territory (the size is going to affect the shipping price more than the weight).
For pricing, FedEx, UPS and the Post Office all let you get shipping estimates online. Measure to the next whole inch and use the family bathroom scale for the weight. I find that FedEx Ground/Home Delivery is often the cheapest for bigger stuff. If you use a local FedEx or UPS retail shipping store, expect to pay about $4.00-$7.00 more than the online price at the retail location. No need for "insurance" coverage over and above whatever standard coverage the shipper offers. In the event of damage or loss it would be hard to collect anyway as you would be hard pressed to show what you paid for the wheels or what their retail value is.