17" alloy spare wheel query

vikingaero

A lot of cars come with steel spares that are 1 inch smaller than the alloys/steel wheel fitted on the axles. As long as the tyre on the smaller steel spare is similarly sized in profile and width then it's not a major problem.

As LondonTiger has said it's hard to come by a decent range of 17" steel wheels whereas 16" steel wheels have loads of choice. Some cars are limited by the size of the spare wheel well too so only a smaller wheel might fit.

Richard53

mutley74 wrote: »

I had the issue of different steel bolts on my current car so had to buy extra bolts for £16! (better safe than sorry).

but will having a different size spare limit its speed use? if so it worth having this size spare?

You were wise to do that. Steel and alloy wheel bolts are often different for different models of the same car. I've had Land/Range Rovers with alloy wheels and steel spares, and the bolts were always different, mainly the degree of taper. You could get away with the 'wrong' ones at a pinch, but only a strictly get-you-home measure.

I would have thought that if the rolling radius was the same (whatever the rim size), then you could drive normally without noticing much difference. But if the OP is the type who pushes things in corners and drives to the limit, then he/she might find that there are very different characteristics at that corner, possibly dangerously so. Keep it sensible, should be OK.

mutley74

WTFH wrote: »

What size are the tyres on the 17" wheels? Without knowing that, we can't say whether the 16" one is ok or not.

current tyres are 225 45 R17


(I am a careful driver don't push to limits and legal boundaries, but as driving is the most dangerous task in my day keep it as safe & risk free as possible)

OddballJamie

mutley74 wrote: »

current tyres are 225 45 R17


(I am a careful driver don't push to limits and legal boundaries, but as driving is the most dangerous task in my day keep it as safe & risk free as possible)

That's a good match for 16" and 17". My summer tyres are 225/45/17 and winter are 205/55/16, it'll be fine.

vaio

http://www.motuk.co.uk/manual_410.htm is clear that tyres/wheels of different sizes across an axle is a fail.

I know odd sized space savers and similar can be lawfully used but only at < 50 mph but if I was getting a *new* car then I'd want a spare that could be used under all circumstances i.e. the same as the four fitted to the car

molerat

The 16" is around 8mm (.38%) smaller in circumference and will rotate 4 times per mile more, just about as spot on as you will get.

molerat

vaio wrote: »

http://www.motuk.co.uk/manual_410.htm is clear that tyres/wheels of different sizes across an axle is a fail.

I know odd sized space savers and similar can be lawfully used but only at < 50 mph but if I was getting a *new* car then I'd want a spare that could be used under all circumstances i.e. the same as the four fitted to the car

The problem with many cars now is that there is nowhere to put a full size spare or in many cases a spare at all. I know that some cars can have a 100mm false boot floor foam spacer if you want an alloy spare but obviously eats up a lot of boot space.

vaio

yep, and if there was only room for a space saver then you are stuck with it but in the OP's case they can fit a "full size" one so I don't see why they would even consider having a smaller steel with bigger tyre rather than a normal alloy & tyre

red_eye

mutley74 wrote: »

my car has 17" alloys. Dealer supplied me with a 16" spare rim fitted with a 205 R16 55 tyre...is this right? (as it was same size tyre and rim I had on my previous car which had 16" alloys then)
I thought tyre size had to be larger outer diameter for 17" wheels?

so your 17" wheel on the car would be a 205/50 17? if it is not the dealer supplied you with an incorrect tyre

go up to the next size in tyre width or wheel dia you go down a size in profile and vice versa

red_eye

vaio wrote: »

http://www.motuk.co.uk/manual_410.htm is clear that tyres/wheels of different sizes across an axle is a fail.

I know odd sized space savers and similar can be lawfully used but only at < 50 mph but if I was getting a *new* car then I'd want a spare that could be used under all circumstances i.e. the same as the four fitted to the car

it is a fail if presented at the test. but perfectly legal to as a temporary "get me to a tyre shop"

if you want a same size wheel you will have to buy one, steels are cheaper to produce and supply