Dhameystir weedha soo socota: Sanadkii 1951, Mutual waxay si weyn kor ugu qaadday sicirkeeda xayeysiinta, kafaala-qaadeheeda ugu weyn, Perfect Circle Piston Rings, ayaa ka laabtay taageerada. Mutual ayaa ugu dambeyntii go'aansatay inay joojiso daabacaadda dhacdada, waxayna u muuqatay in muddo ah in tartankii 1951 aan lagu baahin raadiyaha. Bilowgii Maajo ee
1951-kii, madaxweynihii Speedway Wilbur Shaw ayaa heshiiskii daqiiqadii ugu danbeysay u saxiixay WIBC si ay u daabacdo tartanka, iyadoo Sid Collins uu yahay xariir. Qaabka WIBC wuxuu raacay kan Mutual, oo leh daboolida tooska ah ee bilowga, dhammeystirka, iyo cusbooneysiinta xilliyeedka tartanka oo dhan. WIBC waxay bixisaa caymiskeeda qiyaastii 25 kale oo ka tirsan Mutual.