Not sure what you mean by the above - are you indicating the roof tracks got damaged or just that the tracks you drove on were rough :)
The load rating for the roof is 75kg - indeed is similar for most cars. However that is the rating for a moving vehicle - static load limits are not given - obviously if this were not the case most roof top tents full of porky mummy and daddy would exceed roof limits.
Cheers
Garry

