I have 29 inch wheels - measured with a measuring tape. So I bought the next size up and they fit perfectly. Plastic hooks attached to elastic material are useless. I'm not a flexible woman. I can't reach behind the wheel to hook them together and there's nothing to tie them to under the car or in the wheel wells. So I use bungee cords to secure the lids. We have severe thunderstorms with strong winds here in Florida, so I find it necessary to tie them down. I don't want to look for covers all over the place. I use these covers to protect my tires from the sun - they do the job perfectly. When I remove the covers, the tires feel cold.