Asking a question for my son.

He has a VW polo 1.2s 2010. A few months back he'd got a slow puncher so went to a local tyre fitters to get replacement. Whilst there he was told that the tyres fitted are a different size to what was originally on car. He's was told original should be 165/70r14 but on car at the moment are 175/70r14. With that the guy said he had none in stock so rang around to get hold of one for him which eventually he did.

Is there a way that I can find out what tyres should be fitted to his car? Halford show all different sizes and so do kwik fit.

Or could someone on here tell me what should be fitted by using Reg to get info for car.

Hoping someone can help.