Rim Trim refers to plastic or chrome colored materials that is placed on the outer ring of a vehicles rims.
Rim trim most commonly can be found on sports cars with black colored rims or police cars. Most of the time rim trim is found on vehicles with black or grey shaded rims.
Rim Trim is made out of either plastic or more commonly, stainless steel.
Rim trim is like a hubcap, the size of hubcap to be placed on a vehicle would be the same as its rim size. Ie: If a vehicle has 15" Rims, then it needs 15" hubcaps. Same thing applies for rim trim. Vehicle centercaps don't usually come in sizes but are made specifically for a vehicle rims. Most commonly found on police vehicles.