BBS RFRF Wheel Technology: One Piece Die Forged Aluminum Wheel Weight optimized by FEM analysis Expand Part Size Bolt Circle ET Wt. (lbs) CB RF 504 17 x 7. 5 5 100 48 14. 5 PFS RF 505 17 x 7. 5 5 112 45 15. 6 PFS RF 513 18 x 8 5 120 35 17. 4 PFS RF 514 18 x 8 5 114. 3 43 18 PFS RF 515 18 x 8 5 100 45 17. 8 PFS RF 516 18 x 8 5 112 45 18. 2 PFS RF 517 18 x 8 5 120 48 18 PFS RF 519 18 x 8. 5 5 114. 3 50 18. 1 PFS RF 520 18 x 9 5 100 45 17. 9 PFS RF 521 18 x 9