Traces on the track

hi,

maybe it is normal or maybe it is a bug.. I don't know :)

the supercars (standard cars) and the sportcars (two black lines) seems to make tires traces on the road during the first part of the first lap from the practice session.. after there is no trace at all anymore (practice nor race)

at the contrary the "look oldies" cars make traces during the whole session (practice and race)