why nitrogen gas is filled in tyres instead of air ?

Pure nitrogen does not contain water vapour whereas air contains. so in case of air oxidation occurs and corrosion of wheel rim occurs. nitrogen. in case of air pressure changes with temperature and while riding temperature of wheel increases and inflation pressure changes. so tire maintanance cost increases. in case of nitrogen pressure change is vary vary small. nitrogen is very less permeable through rubber. So altogether inflation pressure change is very less for nitrogen.