Thanks, I obviously misunderstood what you meant!There is no need to do 20mph carolyn, if they were cracked they wouldn't let you take it home, they must have a spec to check them to if it's out of this spec this could lead to cracking, the crack on the pic I posted is worse case scenario could have been a white van man bouncing up and down kerbs all day to cause it, anyway fingers crossed that you don't need them