Tyre and wheel sizing

[Xantidote]

Tried searches but no joy.

Are there any guidelines/regulations regarding the width of tyre that may be fitted to a particular width (J) wheel?

My query is in part because am thinking of wheels & winter tyres, and also partly because I nearly bid this week on a set of the C5 Series 1 alloys from a 2002 (90/110?) car, with a view to fitting them my S1 1.9TD.

My S1 Xantia rides on 185/65/15 steel wheels, 5 1/2 J. Firstly, ignoring profile & speedo issues, could I fit 195 or 205 width tyres to wheels with 5 1/2 J, or would I have to go up to 6J?

Secondly, if I procurred some 15" 6J wheels, either in steel or alloy, would my present 185/65 Michelins fit them OK.

What I did glean from my searches is to be aware of the insurance implications, and presumably any 6J wheel would have a slightly increased offset. I'll the same questions of my local tyre fitters when I next pass them.

Thanks guys

[Citroenmad]

You will often find in the small print on a tyre that it advises the width of wheel to fit them too. Though I think it might be a minimum width and not maximum.

185s on a 6j alloy will be pushing it, they will be slightly stretched possibly. Some tyre fitters might not want to fit tyres to such wheels if they will be stretched. It will also leave the rim of the wheel exposed and so easily curbed. Im not sure if that is a legal issue or not, many VW drivers run silly stretched tyres, 165s on 7js for example.

I would be tempted to fit the wider tyres on the alloys and keep the 185s on the skinny 15" steels.

[addo]

205s on a 5½J is pretty ballooned out; I know from personal experience. Sidewall stiffness also affects how well a tyre deals with non-design rim widths - it's best to investigate the particular proposed tyre via their manufacturer or agent.

Be advised the offset on a 6J C5 wheel is quite different to the offset on a 6J Xantia wheel.

[Xantidote]

Chris and Addo,

Thanks guys - greatly appreciate your comments

Addo - interesting what you say about the C5 offset. I hadn't yet done any checks on that score, and based on what you say, I'll probably not go further down that avenue. I'd assumed there'd be not much difference between Xantia and C5 offsets, partly as the C5 followed the Xantia in production terms, and also because 1-2 years ago, I saw a Xantia for sale with C5 alloys fitted, though never went to look at the car. Maybe the guy didn't know what he was doing?

All comments gratefully received

[addo]

Official offset on a Xantia 6J steel is either 15 or 18 (15 being far more common). Offset for a 6J (15") steelie on an early C5 (original grille or facelift) is 18mm.

With 16" rims the C5 went to an offset of 26mm and rim width of 6½J.

[mendedit]

Try,
http://www.carbibles.com/tyre_bible.html" onclick="window.open(this.href);return false;

http://www.tyresave.co.uk/tyresiz2.html" onclick="window.open(this.href);return false;