@rclocher3's electrical tape is the easier way to go, but I often use strips of old tube to wrap things of this nature.
To keep the wrap in place I dab some vulcanizing fluid hither and thither along the underside.
This saves electrical tape for electrical things, is perhaps a bit more rugged than tape, and also provides fodder for people who would mock me on stackexchange.
bicycles.stackexchange.com/users/25313/Fing Lixon
I've used some heat shrink in the past for things like this, it's used in situations to replace electrical tape.
Usually, I use a soldering iron to heat it up after getting it in place, but a hair dryer might also work
but it'd take a little longer though.
I originally used electrical tape - the "rubbery-ness" of the tape was quite appealing as it stopped things slipping, but it went gooey after a few months.
bicycles.stackexchange.com/users/10916/jonifen
When the orange rubber padding dried up and cracked away on my guitar stand, I peeled it off and replaced it with clear, PVC hose of a similar diameter, plugging the hose ends with the original plugs.
It provides good cushioning.
PVC is the same thing as what is already on the hook, namely vinyl.
The word "vinyl", when it refers to a material, is usually just a short name for polyvinyl chloride (PVC).
PVC hose is an easy way to effectively get a really thick vinyl coating onto a steel rod instantly, without any dipping or painting.
Because some of the curves are rather tight, the hose inner diameter should be generously larger than the hook's diameter.
The extra width, thickness and air gaps between the hose and the hook will also provide better cushioning than the original coating, letting you be more abrupt in your movements when you hang the bike or take it down.
It doesn't specifically have to be PVC.
I chose it for that guitar stand because it's durable: it will last long without drying up and cracking like the original covering.
Being transparent, it also looks kind of good on that particular guitar stand, over its chrome tubing.
Tip: if pulling hose onto the hook gets a little difficult, in spite of good sizing, a dab of vaseline will help.
bicycles.stackexchange.com/users/5088/Kaz
There is a liquid sold in hardware stores that is advertised as being a fast and easy way to make a rubbery coating for a tool handle: just dip the tool into the liquid and let it dry.
In the US it's called "Plasti Dip".
You might try that.
Personally I think I'd just wrap the hooks tightly with two or three layers of electrical tape; the tape stays put better if you cut the tape with scissors rather than stretching the tape to break it.
Electrical tape is sold in many colors these days, so you could match the color fairly closely if you or your significant other is picky about such things ;)
bicycles.stackexchange.com/users/26527/rclocher3
The obvious answer to me is (old) handlebar tape!
bicycles.stackexchange.com/users/106/Anthony K
Vinyl covered wall mounted bike hooks coating is wearing away due to use. What can I use to cover them so my wheels don't get scratched?  Using These type of hooks:
Rubber on wall mounted bike hooks is wearing away. What can I use to cover them so my wheels don't get scratched?
bicycles.stackexchange.com
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bicycles.stackexchange.com/questions/41542
bicycles.stackexchange.com/users/2997/Benzo
Worn rubber on wall-mounted bike hooks can be replaced with olf pieces of tube, heat shrink, electrical tape, pvc hose, handlebar tape and liquid rubber product. Possible coverings include pvc tubing or hose, heat shrink covering or wrapping in electrical or handlebar tape. Electrical tape may be too thin and easily damaged for this purpose. Hooks can also be dipped in coating liquid sold in hardware stores.
Possible coverings include pvc tubing or hose, heat shrink covering or wrapping in electrical or handlebar tape. Electrical tape may be too thin and easily damaged for this purpose. Hooks can also be dipped in coating liquid sold in hardware stores.