Thanks for that suggestion. It might work to move just some tires (without wheels), but maybe not secure/stable enough to store four full 20-inch wheel+tire combinations.
I was thinking about something like this is (except with a secure U-shaped handle to make moving easier):
or
The trouble with all the tire/wheel dollies on Amazon is that they are now apparently all made of some kind of plastic. Reviewers complain that they break or otherwise don't hold up.
I am going to try to take a screen shot of one of the professional ones (from F1 racing) the next time I see one being used in a racing paddock.
Well, a most cursory search shows you can get one off Amazon for $229: https://www.amazon.com/PRIMECOM-Level-2-Electric-Vehicle-Charger/dp/B07B8W83RT/ref=mp_s_a_1_3?keywords=level+2+evse+nema+14-50&qid=1564781060&s=gateway&sprefix=level+2+evse+&sr=8-3
I replaced the frunk spring with this one and I can easily close with one hand now.
Century Spring C-77 2 Count 1-7/8" Extension Springs with 11/32" Outside Diameter https://www.amazon.com/dp/B000H5SJGA/ref=cm_sw_r_cp_api_i_OyYzDbMDNBKG9