(Set di 4) Tappi per valvole a spillo in alluminio, ermetici, per pneumatici

The idea is nice and they look slick installed, but the silicone inner is to soft and the aluminum cap is about 13mm to long.
I originally ordered a set of 20 pcs and within weeks two caps came off while driving, the silicone inner is to soft and with every bump slowly comes off, and another thing I noticed was the caps are to long, the lug stud only goes in half way maybe 12-13mm so you have a lot of dead air space and with all the weight to the outside of the cap and all that extra space causes the caps to come loose.
I'm going to try to either shorten the caps or find some type of glue that can be removed easily when I have to service the wheels.