One of the questions we get asked the most is if our mud flaps are compliant with MSA regulations for mudflaps and splash guards?  This is what the MSA have to say on the matter   “b) Mud flaps behind all four wheels extending 4mm each side of the tyre tread and a maximum of 8mm above the ground are mandatory.” http://members.msauk.org/site/cms/newsarticle.asp?chapter=1&nid=958