What's the audi s4 lug nut size?

The Audi S4 has a lug nut size of M14 X1.50 with a hex size of 17mm. This means that if You need to remove Your lug nuts You will need to use a 17mm socket. You can use an impact driver while removing lug nuts, but You should never use one when reinstalling them. An impact driver can put excessive torque on the lugs and that can strip out the studs that are on Your wheel hubs. When reinstalling lugs You should use a calibrated torque wrench. This will allow You to make sure that they are on and matching the manufacturer's recommended torque specification to prevent them from coming loose while You are driving.