I have a 2001 Focus Saloon 1.6 on 185/65/14's steels

Now the steels have more rust on then my old Land Rover and I lose
1 - 2 PSI every day

Focus came with 14's 15's 16's Wheels it say for my car ?? I wanna keep the 14's maybe the 15's if the speedo with stay the same

Now I have looked on Ebay been to part worn tyre places and I have only seen ones that are no better then the ones I have now any ideas where to get some would be good ... Thx