Ricta 53mm Pro Speedrings Curren Caples 81b Wheels (Set Of 4) Curren Caples Pro Speedrings are harder street/park wheels but that ring inside is a softer urethane that aborbs that hard chatter you feel when you ride hard wheels on rough ground. Speed rings are some of the faster wheels you can ride on smooth surfaces. Not a soft cruiser wheel. 53mm in size and 81b (roughly the equivelent to 100a).