On 14/02/2019 17:07, NY wrote:
"dennis@home" wrote in message
news
I *thought* that a spacesaver spare tyre was always (nominally) the
same OD as the wheel that it is replacing, allowing for different
amounts of tread wear, and that it was only the tyre *width* that was
narrower. I agree that one wheel may be a different size to the
other, but that is immaterial as long as the OD of the tyre is the same.

They are frequently smaller all around.
The limit to how small they can make them is the clearance on the brakes.

And how much the car sags at one corner because one wheel is smaller.
When I can be arsed, I'll go and measure my spare against a full-size
wheel. They look the same OD and the car looks level, without a dip at
one corner making the opposite corner high and hence less downward force
on that wheel.

Certainly I've not felt any pulling to one side on the steering, with
the spare on the front or the back - I was amazed at how little it
affected the handling of the car, though I'd be more cautious on
cornering and I'd restrict myself to the 50 mph and 50 miles limit that
they always say.

I would check that it doesn't say 50 km/hr.


Gone are the days when your spare is fully-interchangeable with the four
running wheels and can be driven as far and as fast as you like without
any limit. I really wish the UK would mandate cars to be designed so
they can accommodate a full-side spare (steel rather than allow wheel,
but otherwise normal tyre) as used to be the case until corner-cutting
took over. Cars always had a recess in the boot floor or else a cage
under the boot for the full size wheel - or on some cars like the Ford
Zephyr and some small Renaults it was under the bonnet. Nowadays the
boot doesn't seem any more capacious but there's allegedly no room for a
full size wheel in boot - all the pain, but with no perceivable gain.

I think even our big Honda CRV has a space-saver spare, and that's got
plenty of space below the boot floor to take a full-height spare.

Car manufacturers say "oh, it's not a problem - put the spare on and
drive to a tyre place". Not at 10 PM on a Sunday when you're about to
start on a long journey. I don't think I've ever in all the years I've
been driving had a puncture that's happened during shop opening hours -
it's always late at night or on a Sunday that I discover it. Until
recently it was a minor nuisance which delays me setting off by 10 mins
or so to fit the spare, and then take the dead tyre in to be repaired at
a later date when I'm not in a rush to be somewhere. Now it's a
show-stopper which means waiting till the following morning to set off
after I've been to the garage - hoping that they actually have the right
size in stock and I don't have to wait another 24 hours till they've
ordered one in.

Think yourself lucky, they don't do a space saver in my car.
But as its a motability car I might just ignore the flat and drive to a
tyre place if its close or call them out if it isn't.

I suppose I could try the junk in the can first if I can get to the tyre
without getting run down.

The last puncture I had I drove a couple of miles on the M^ roadworks to
avoid stopping on a live lane, its fine as long as you can do at least
50 to keep the tyre up by centripetal forces.
Then I had the RAC come and change it while I watched from behind the
barriers.