Ecoboost 1.0 

Current tyres 195 55 15 H

However, every website I put the registration into tells me I need: 195 50 15H

Naturally, I've gone for what's already on the car, but can anyone explain the disparity, considering there is about £15 difference between the sizes.

Thanks in advance 

Check the owners manual for the correct size, maybe they've been change and the wrong sized fitted.  I doubt if every website is wrong.

Enter your VIN or registration number on the Ford ETIS website and you will get all build specifications including the tyre size that was factory fitted.

2 minutes ago, JW1982 said:

Enter your VIN or registration number on the Ford ETIS website and you will get all build specifications including the tyre size that was factory fitted.

Cheers- came with 55s, double checked on fitting companies website, most say I need 50s.  At least I've booked the right ones. 

19 minutes ago, Gaskell71 said:

Check the owners manual for the correct size, maybe they've been change and the wrong sized fitted.  I doubt if every website is wrong.

The manual is just confusing- 2 options for R15s up to 100mph 1.0L Ecoboost, 185/55/R15 or All engines 195/55/R15, so the all engines are the tyres I have, but have an 1.0L ecoboost engine.  

My Ecoboost 100 - Fiesta Titanium has 195-50-16 tyres.   Every website I look at for tyres wants to sell me 195-45-16.

Check the door, there is usually a sticker on the drivers side (passenger side for us) for the tyre pressures for each of the wheel sizes for the car - the 195/45/16s are 3.5% difference in circumference so not recommended as the speedo will be out. 

I would never rely on the tyre size from the reg. no. on those websites. My wife's Mazda2 TS2 has 15inch wheels but from the reg. no. it always says 16inch with a lower profile. I am sure the wheels she has are the correct ones.  A friend also had same discrepency with her Golf.