I very recently bought my first car which is a 2016 Fiesta Zetec S and it came with 17 inch alloys running 205/40 tyres. I want to replace the tyres and I am considering maybe getting some new wheels (specifically, Rally Racing wheels from OZ Racing). The minimum available diameter on these is 17 inch as I currently have. I like the look of the bigger wheels, but am wondering if tyres with slightly bigger sidewalls for example 45s would fit on my car with these wheels, or would they be obstructed by the wheel arches?

Also, my speedometer currently reads about 4mph above my actual speed which I think is normal, bigger tyres would increase the speed but would this not be a problem as it may just bring it up to the reading speed?

Hi Jeremy, welcome.

There have been many threads on this over the years, recent one here:

https://www.fordownersclub.com/forums/topic/165904-another-wheeltyre-question-w-tyre-compatibility-sorry/#comment-1146282

45 profile as you suggest will reduce your speedo over-read. Also less liable to pothole damage.

Have a play around with a calculator such as this to see the effect of various wheel/tyre changes:

https://www.willtheyfit.com/

Thanks that helps a lot, also wondering if anyone can tell me does a wheel with a width of seven inches fit a 205 or even 215 tyre?

Yes.

Legend thanks mate

41 minutes ago, TomsFocus said:

Yes

Another useful table there, Tom!

The Mk 7 factory 17" options were 7" rim width, for which the 205 tyre is pretty much an ideal fitment.

The Mk 8 however came with 7.5" width for both 17" and 18" options, but still 205 tyre, which is the recommended minimum. Never figured that one out.

@Jeremy Cole this thread from another forum has shots of a Mk 7 on both 205/40x17 and 205/45x17 tyres which gives an idea how they look.

https://www.fiestastoc.com/threads/205-45-17-tyres-fitted-to-standard-rim.326055/

👍