Probably cheaper to make with elastic hems.
I don't know much about them as I don't use them. The one time I did it was nothing but a bugs/critters and dirt trap.
If you're not fussy about appearance, and just want to hide/protect the tire from the elements, you could try a big green trash bag with a drawstring.
Mike. Comments are anecdotal or personal opinions, and worth what you paid for them.
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????)
2016 Sunstar 26HE, V10, 3V, 6 Speed (sold @ 4600 miles)
2002 Roadtrek C190P (sold @ 315,000kms)