I've just bought a three-month old Ford Grand C-MAX. All the Ford Brochures state that the tyre size is 205/55/R16, but this one has 215/55/R16s fitted. according to the handbook I have, either size can be fitted, and the Ford Accessory Brochure states that either tyre will fit the standard wheels.

I phoned Ford Customer Services, and they directed me to the Ford Technical helpline. But the guy answering the phone hummed and hawed, and only when I pointed out what the Accessory Brochure stated, did he say, 'well it must be okay to fit either'.

He didn't exactly fill me with confidence.

Interestingly, if you look at the owners' manuals, which you can download from Ford's website, the one for 2010-September 2012, has both sizes listed. But the downloadable manual from Sept 2012 onwards, only has the 215/55R16s (for the 2.0D Engine) as the tyre size (despite the fact the brochure still says 205/55/R16's)!

The reason I'm asking is that I have a set of Winter Tyres which are 205/55/R16s, and I want to use them on the Grand C-MAX in the winter. But now I'm slightly concerned that my Insurance company won't accept them - OR that it may not be safe to drive the car with the 205s.

I did call my Insurance company only to speak to an adviser who just kept repeating, 'you have to fit the standard tyres'. Tf only we knew what the standard tyres were!

I sent Ford a tweet and an email, asking the question, but sadly they don't seem to want to reply. Honest John, can you help?