I am looking to change the wheels on my Fiesta for smaller ones with bigger tyres to cut down on road noise (and tyre cost)..
I have the 08 Fiesta Zetec Blue, currently running 16" alloys with 195/45 R16 tyres.
I have found some 15" steel wheels with 195/50 R15 tyres from an 06 Fiesta.
Does anybody know if it will be possible to do a straight swap? Will the new wheels fit my Fiesta (as both are the same model)? And will the car need reprogramming?/How much will this cost?
Full Version: Changing Wheels - Fiesta 08 From 16" To 15"?
If they are off the same model/mk Fiesta then the wheels will fit.
The overall diameter of the wheel is the important dimension as this will affect your speedo reading. There are plenty of online calculators which will work this out for you from the tyre size.
For your's - your current wheels are 58.19cm diameter and the wheels you are considering are 57.60cm diameter. This will make less than about 1% difference on your speedo reading.
TBH, this will be fine as speedos are a bit out to start with (if you have ever looked at your speed on a sat nav and compared it to your speedo you will see what I mean - the sat nav is correct!) and an additional 1% isn't a lot.
As your new wheels are a bit smaller your speedo will under-read a bit. So, with your new wheels, when your speedo says you are doing 60mph you will be doing about 59.5mph. Not a big deal!
No reprogramming will be necessary!
The overall diameter of the wheel is the important dimension as this will affect your speedo reading. There are plenty of online calculators which will work this out for you from the tyre size.
For your's - your current wheels are 58.19cm diameter and the wheels you are considering are 57.60cm diameter. This will make less than about 1% difference on your speedo reading.
TBH, this will be fine as speedos are a bit out to start with (if you have ever looked at your speed on a sat nav and compared it to your speedo you will see what I mean - the sat nav is correct!) and an additional 1% isn't a lot.
As your new wheels are a bit smaller your speedo will under-read a bit. So, with your new wheels, when your speedo says you are doing 60mph you will be doing about 59.5mph. Not a big deal!
No reprogramming will be necessary!
Hi what do you plan on doing with your old wheels/tyres? I have the same car 
What millage are you getting on a set if I may ask?
Further to what rojariggs has said all speedos unless accurately calibrated are 9-10% over reading I've noticed this by going into the diagnostic mode on my fiesta to read the actual road speed and have found that it's about 5ish mph over reading but dont go around taking that as been true stick to what youre speedo says. Smaller wheels will mean a greater over reading and theoretical lower top speed so engine rpm will be higher for the same speed and gear (potentially use more fuel) but the difference in sizing is negligable.
Dec.
What millage are you getting on a set if I may ask?Further to what rojariggs has said all speedos unless accurately calibrated are 9-10% over reading I've noticed this by going into the diagnostic mode on my fiesta to read the actual road speed and have found that it's about 5ish mph over reading but dont go around taking that as been true stick to what youre speedo says. Smaller wheels will mean a greater over reading and theoretical lower top speed so engine rpm will be higher for the same speed and gear (potentially use more fuel) but the difference in sizing is negligable.
Dec.
The overall rolling circumference depends more on tyre size, not the wheels size, the chances are the 15"s will go on, but it might be worth checking the inner wheel doesn't foul the brake caliper(s) (drums)... 
Full Colour Version: Changing Wheels - Fiesta 08 From 16" To 15"?
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