First of all speak to your insurers. If you don't tell them about a change to your car, you could be in serious trouble if you need to make a claim. You'll probably find they'll want an increase in premium for changing your wheel/tyre size.

If you're still not put off, this site will tell you the change to your gearing different wheel diameter and tyre width will make (just after halfway down, 'A tyre size calculator')

www.carbibles.com/tyre_bible_pg4.html

Finally. Ford spend millions on research into design, materials, safety,comfort and handling of your car. Do you think your change will be an improvement?

I was hoping to pick up some focus zetec alloys and not have to tell the insurance as they are a standard issue but on a different model, is this the case ? Of course if they have to know then they have to know I agree.

You're right - alloys were standard on some models and not others, but then the different models were in different insurance groups to reflect the differences in trim/spec/performance.

Upgrading steel wheels to alloys definitely counts as a modification so you should really inform your insurance company if you do this. Some people probably wouldn't bother but it's not worth the risk IMO.

It might not make much difference to your premium, although there would probably be an admin charge at least - I'd phone and ask first if I was you.

HI. been there done that..and paid for it...TWICE

I used to own a Y reg mk3 mondeo 2litre LX. standard 16" steel wheels with plastic trims all totally standard. When i needed 4 new tyres I did some searching and found a Ford breakers in Essex, (I live in Oxfordshire) I then bought 4x mondeo ghia 17" alloy wheels+ tyres for my car for £100 less than getting standard replacement tyres for the 16" wheels. (rep had written off his car 20miles after picking it up,. the tyres still had the waxy green marking around the tread...so I bought wheels and tyres for less than a set of 16" tyres for my car....but......thought like you...standard wheels on the same model..insurance said it was a modification and loaded me £50. the same amount as if i'd just bought some aftermarket stuff from Halfords...

had the same on another previous car had a impreza sport (non turbo) 2003 reg. with 15" alloys and replaced them with impreza wrx 17" wheels insured through a different company,,,and yep £50 increase,,,as said check the radius and offset to make sure the speedo and mileometer arn't affected.

paul.