16" versus 17" wheels ?

Are you saying your tyre options are 215/50/17 vs 215/55/16?

The difference in circumference and hence speedo or odometer reading is immaterial. These are direct swap sizes on any vehicle. 197.1mm (17") vs

195.9mm (16") - about 0.6%.

50 series tyres are standard on many cars these days and the difference between ride quality on those vs 55 series is again unnoticeable. It's only when you get down to the 40 and 35 series rubber band jobs beloved of the idiot tuning fraternity that it might become an issue.

Buy whatever you get the best deal on. Rotate the tyres after a couple of years and they'll last for 25k plus miles so it won't be an issue for several years at your stated annual mileage.

I routinely run either 205/50/16 or 205/55/16 tyres on my Focus depending on what comes up for free from my mate at the local tyre skip and you can't tell any difference behind the wheel.

If they are, the price difference is a tenner a corner for a mid-range (eg. Falken).

Not really worth worrying about.

Ah remember, when ah were a lad, and 70 profile were low, and 60 were reet rubber-band...

My MX5 runs on oh-so-retro 185/60-14s.

Back in the day, they were the sign of a 'hot' car - just about every

80s hot hatch ran them, and they were the control tyre in a couple of tin-top racing series.

My Alfa 75 runs 195/60-14s, which seems ludicrous these days, for a car in the 'junior exec' class.

Indeed.

CX GTi - 195/70 14... Saab 900 T16 - 195/65 15...

The biggest problem with running high performance stuff of that era now is that there's so little choice of decent high performance rubber.

We won't even go near the 210/55 390 on the CX turbo!

Tell me about it.

The choice offered when I needed a pair for the 75 was a whole host of Ying Tong Iddle I Po ditchfinders. Or the Cooper Xeon.

I fitted the Coopers.

Not exactly an option in this case, the dealer is pushing some Focuses out with the 17" wheels as part of an appearance pack, with a decent discount.

That's what I am doing, see above. My particular car also has door edge protectors which pop out when the door is opened. I thought this was a stupid gimmick which was bound to go wrong until I saw them in action, - a very simple mechanism.

Thanks for your input.

How does it protect it from another door being opened onto your car, though?

How did I know someone would ask that question? For the next few months I will be parking at least 5 yards from any other car. ;-)

With a new car, you can park miles away from any other - but will find it surrounded when you return. ;-)

which is exactly why my Focus has a nasty gouge in one door, parked on the far side of a largely empty car park, when the proud owner returned to it he said he could have cried, it was only a year old at the time.

[...]

I parked a nearly-new car in exactly the circumstances you describe. When I returned, there was a single car parked next to it. my car had a clear 'door-dent' and scratches on the bonnet where a bag or something had been dragged across it.

I left them a note saying "Thanks"; I didn't have any paper. Or a pen. I did have the tip of a very sharp car key however...

Chris

Had you removed the bubble-wrap by that time?

Not necessarily. It may well be the exact same car but for optional rims/ rubber.

Mechanical equipment, yes. I don't think I've ever seen different CO2 for the exact same mechanicals but different trim level, unless the trim difference includes something external which would affect aerodynamics or have a very signficant effect on weight.

It seems obvious from here. Different wheels and tyres will have a marked effect on rolling resistance. Wider tyres will have a significant effect on aerodynamics, as even may differently styled rims. They may well have an effect on gearing.

Compared to that, a few dozen kg (at most) of weight difference from internal equipment will have a relatively minor effect in a ton and a half of car.

I know there are dickheads who put on 20-inch rims, then need 30 profile tyres, with hardly any sidewall. If you have McPherson struts, these ultra-low profiles are actually worse, due to the camber roll.

If they are optional, they won't be on a stock model.

The current BMW site quoted does that.

The claim is only for wheel diameter.

The tyre width is supposed to be identical for the Focus appearance pack. Yes the gearing will make a difference, but that is not wheel diameter.

Nobody claimed that weight was important.

The claim is for the standard-fit wheel and tyre combinations fitted at the time of the CO2 testing.