Hi, Thanks to all, i know now that "slowdown building" are called "speed bumps" (but also as in France "sleeping policemen"....) Difference is the size ! In France we've short speed bumps (4 to 6 inches height and 8 to 10 inches widht) but also long speed bumps: same height but the widht goes from 6 feet to 10 or more. The problem comes from those which are 6 to 8 feet :You have the front wheels ahead the bump and the rear wheels backward. Imagine where is the center of the car if the speed bump is too high (some of them are higher than 6 inches ...) and not enough long !! My car has radial WWW Coker tires 225/75/14. Overall diameter is around 27.6 inch. Original 9.50 x 14 have an overall diameter of 31 " .... the car is too low in front, not in rear; need perhaps KYB shocks in front (mine came from Kant...r, not made in USA..) -- Philippe COURANT (Pau, France) Imperial 57 Crown convertible Buick 58 Roadmaster sedan - American Car Club de France (ACCF) : http://www.accf.com - Chrysler Imperial France : http://www.ifrance.com/c-i-f - Cadillac " Standard of Excellence " : http://www.ifrance.com/accf-cad - SportsCars : http://www.ifrance.com/accf-sprtcar