The cheap eBay ones don't have enough glitter sparkle in them. Use a heat gun and heat the clips at the back of the centre cap to soften them but be very careful not to melt them then bend them more than vertical let them cool. Just so happens I have a brand new set of Anthracite ones for R26 rims but I am having trouble getting the paint colour correct on the rims and also old ones so you can see the difference. They don't need an extremely tight fit as they are in the centre of the wheel but here it goes. You can see the old one with constant pressure the tab is not vertical and is bending inward slightly.