People love the look, weight, and strength of the TE37SL and TE37RT. However, many of those same people don't use them on the track and don't like the open center of these wheels. While the RT and SL wheels were not originally designed to take a center cap, Rays has come up with a solution: the Volk Racing SL/RT Center Cap Adapter.
It is designed to work with the TE37SL and TE37RT without modification and will work with most wheels in 5x114.3 and 5x120 bolt patterns. The 5x114.3 will use a 3mm o-ring while the 5x120 will use the 2.5mm o-ring.