They are sized by tire diameter (tread to tread) and width (sidewall to sidewall). Sellers may or may not list all tire sizes that fit. Check reviews for accuracy of fit; I’ve had to send some back that were too tight or too loose.
I no longer use one on our Scamp
or CR-V.. Good, tight ones are such a pain to take off and put on I never bothered to check the pressure in the spare. Then I got caught in the CR-V with a flat tire, a low spare, and no compressor.
Something to consider. When towing, I do carry a compressor.