Who knows about tyre sizes?

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I've just bought a used car and it is one of these that doesn't come with a spare tyre, however I have one I already own but it's not the same size and I wonder if I can use it as a temporary spare to get me home or to a tyre fitter in the event of a puncture? The tyres fitted are 185/60 R15 and the spare I have is 195/65 R15. It goes without saying that if the wheel nut holes don't line up then the question is moot but I haven't had a look at those yet.
 
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I presume it is from the same make and model, I believe you can use it as a spare to get to the garage, but if it is the same bolt fitment, I would suggest you put the same tyre size on it.
 
AFAIK

The rim sizes are the same but the tire is larger = don't use
 
ShinySideUp said:
I've just bought a used car and it is one of these that doesn't come with a spare tyre, however I have one I already own but it's not the same size and I wonder if I can use it as a temporary spare to get me home or to a tyre fitter in the event of a puncture? The tyres fitted are 185/60 R15 and the spare I have is 195/65 R15. It goes without saying that if the wheel nut holes don't line up then the question is moot but I haven't had a look at those yet.
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185 is the width of the tyre, 60 is the side wall R15 being the rim diameter.
the issue you have is that the spare is 10mm wider and 10mm larger diameter (5mm on each side of the rim)
for a few minutes drive to a fitter it may not be an issue, id not want to drive far or fast. Google suggests different diameters can damage the differential
 
So based on those replies, assuming the nut layout is the same, I can just get a correct tyre fitted as it will fit on the existing rim?
 
ShinySideUp said:
So based on those replies, assuming the nut layout is the same, I can just get a correct tyre fitted as it will fit on the existing rim?
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Yes, I would also check you have space to store it, as all these new cars they do not have a spare wheel space.:mad:
 
AgentOrange76 said:
185 is the width of the tyre, 60 is the side wall R15 being the rim diameter.
the issue you have is that the spare is 10mm wider and 10mm larger diameter (5mm on each side of the rim)
for a few minutes drive to a fitter it may not be an issue, id not want to drive far or fast. Google suggests different diameters can damage the differential
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Not quite true. The 60 and 65 are an aspect ratio or percentage of the width and not a measurement in mm.

The 185/60 means the width is 185mm and the wall height is 60% of that which means the wall height is around 111mm. The wall height of the 195 tire will be around 127mm.

Have a look at this tyre size calculator where you can compare the size of each.

Tire Size Calculator

Free calculator to find the dimensions of a tire based on its code. It also helps in choosing alternative tire sizes based on rim size or comparing two tires.
www.calculator.net www.calculator.net
 
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sep9001 said:
Yes, I would also check you have space to store it, as all these new cars they do not have a spare wheel space.:mad:
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That's the stupid thing with this idea of giving you a puncture repair kit instead of a tyre, they put the kit in a giant depression in the boot which is strangely just the right size and shape for a spare wheel!! No offence to my wife but at a push, assuming she could get the wheel nuts undone, she might be able to change a tyre, but I find it highly unlikely that she would be removing a foreign object, reaming out a hole in the tyre then trying to get a lubricated mushroom in using a special tool in the middle of winter, at night, in the pouring rain; and to be brutally honest, neither would I.
 
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ShinySideUp said:
So based on those replies, assuming the nut layout is the same, I can just get a correct tyre fitted as it will fit on the existing rim?
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Yes.

ecoleman said:
Not quite true. The 60 and 65 are an aspect ratio or percentage of the width and not a measurement in mm.

The 185/60 means the width is 185mm and the wall height is 60% of that which means the wall height is around 111mm. The wall height of the 195 tire will be around 127mm.

Have a look at this tyre size calculator where you can compare the size of each.

Tire Size Calculator

Free calculator to find the dimensions of a tire based on its code. It also helps in choosing alternative tire sizes based on rim size or comparing two tires.
www.calculator.net www.calculator.net
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This ^^

The tyre on the spare can be a different width & height % really. As long as the rolling radius/overall diameter is somewhere close it will be okay.

It appears I'm 15mm out from my standard spare to the 18" alloys i have fitted :)
 
LeeRatters said:
The tyre on the spare can be a different width & height % really. As long as the rolling radius/overall diameter is somewhere close it will be okay.
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That appears to be incorrect.

This tyre company page suggests that you could have an expensive day, if you mix tyres of different sizes or construction on an axle...

 
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Putting a different sized tyre on your car could be seen by the insurers as a modification, or more specifically an undeclared modification. Music to their ears if you have an accident after sticking it on. A space saver wheel will be different because it is designed specifically for an emergency purpose.

I carry a small repair kit around along with an electric tyre inflator. It's ideal for most punctures and you don't even have to take the wheel off.

 
gman said:
Putting a different sized tyre on your car could be seen by the insurers as a modification, or more specifically an undeclared modification. Music to their ears if you have an accident after sticking it on. A space saver wheel will be different because it is designed specifically for an emergency purpose.

I carry a small repair kit around along with an electric tyre inflator. It's ideal for most punctures and you don't even have to take the wheel off.

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The thing is, I've had a few punctures in my time and probably only about 2/3 of them have been repairable. A simple nail in the middle of the tread is one thing, but a major slice in a sidewall from a bottle bottom will take more than a a bit of rubber glue and a mushroom to fix and that is where the spare tyre comes in. It's curious too that when you see pictures of these kits in operation, the puncture is almost always in part of the tyre between the treads, not through them. Having said that, I do carry a puncture repair kit when I go away on the motorbike -- but carrying a spare tyre in that case is a little inconvenient.
 
Never mess around with different sized tyres on the same axle, it just isn't worth it, tha car will definitely pull to one side and will invalidate your insurance if you have a crash. If you have spacesaver wheels, then you will have to keep your car under a certain speed when you are driving.
 
andya700 said:
Never mess around with different sized tyres on the same axle, it just isn't worth it, tha car will definitely pull to one side and will invalidate your insurance if you have a crash.
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Indeed. :(
 
LeeRatters said:
@AndrewFlannigan ^^ I added in the bit there that you deleted from your quote of Andy's. The important bit. The bit that is relevant to this thread just in case you missed it (y)
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You're writing about emergency wheels, designed for that purpose and legal when correctly used for that purpose. My comment referred to using mismatched normal wheels, intended to be used as part of a pair on the left and right end of an axle, as Andy correctly pointed out.
 
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LeeRatters said:
Yes.



This ^^

The tyre on the spare can be a different width & height % really. As long as the rolling radius/overall diameter is somewhere close it will be okay.

It appears I'm 15mm out from my standard spare to the 18" alloys i have fitted :)
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AndrewFlannigan said:
That appears to be incorrect.

This tyre company page suggests that you could have an expensive day, if you mix tyres of different sizes or construction on an axle...

Click to expand...

---------

AndrewFlannigan said:
You're writing about emergency wheels, designed for that purpose and legal when correctly used for that purpose. My comment referred to using mismatched normal wheels, intended to be used as part of a pair on the left and right end of an axle, as Andy correctly pointed out.
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See above first two quotes. I'm writing about spare/emergency wheels because that's what the thread is about. Every reply prior to your above is about the same.
 
LeeRatters said:
Every reply prior to your above is about the same.
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I can't be bothered with this sort of silly argument. I'll ignore you for a while to avoid disrupting the thread further.
 
Careful - you'll end up just talking to yourself, the rate you claim to be ignoring people!
 
Nod said:
Careful - you'll end up just talking to yourself, the rate you claim to be ignoring people!
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With some of the idiots one meets, I'd have a much better conversation talking to myself! :naughty:
 
gman said:
Putting a different sized tyre on your car could be seen by the insurers as a modification, or more specifically an undeclared modification. Music to their ears if you have an accident after sticking it on. A space saver wheel will be different because it is designed specifically for an emergency purpose.

I carry a small repair kit around along with an electric tyre inflator. It's ideal for most punctures and you don't even have to take the wheel off.

Click to expand...


I think I could be wrong with what I said earlier. I was having a poke around online and whilst I didn't come across anything re. insurance related, it would appear that it's perfectly legal to have a different sized wheel for emergencies (even if not a purpose use space saver), so therefore I would assume it would be fine for the insurance as well. So long as the tyre itself is legal with tread and condition then it should be fine.


There's a wee article here from the AA:

Guide to spare wheels and space saver tyres | The AA

As alloy wheels are now commonplace and car manufacturers are looking for opportunities to cut costs, space and weight, you’re lucky to find a spare wheel in the boot at all. Here are your options.
www.theaa.com www.theaa.com


Tyres on the same axle must be of the same size and aspect ratio
  • Aspect ratio is the height of your tyre’s sidewall as a percentage of its width
  • Your car will fail the MOT if mismatched tyres are fitted
  • The law makes an exception for temporary use spare wheels fitted in an emergency
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gman said:
I think I could be wrong with what I said earlier. I was having a poke around online and whilst I didn't come across anything re. insurance related, it would appear that it's perfectly legal to have a different sized wheel for emergencies (even if not a purpose use space saver), so therefore I would assume it would be fine for the insurance as well. So long as the tyre itself is legal with tread and condition then it should be fine.
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Thanks for the clarification. (y)
 
My car is fitted with semi low profile alloy wheels.
It came with a full size steel wheel and tyre in the compartment in the boot. still brad new.
I know a lot of eople who have boght cars with the same as an optional extre, my previous car was the same
 
As long as the wheel has the correct fitment and the offset is sufficient to clear the brakes then a small discrepancy in rolling radius wont be a problem if you are intending to only use it as a short term replacement to get you home/to a tyre fitters.
 
I've seen a couple of cars with orange space saver spares on all 4 corners!
 
andya700 said:
Never mess around with different sized tyres on the same axle, it just isn't worth it, tha car will definitely pull to one side and will invalidate your insurance if you have a crash.
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Once a certificate has been issued, it is very, very hard for an insurer to avoid paying out to third parties (i.e. invalidate the insurance). Clause 148.2(b) of the road traffic act 1988 makes sure of this. The insurer would have to void the policy ab inito , that is literally the only way they can invalidate it, and when that happens the Financial Ombudsman Service heavily favours policyholders over insurers, as an examinations of its ruling will demonstrate. The threshold to void is very high.
 
onomatopoeia said:
Once a certificate has been issued, it is very, very hard for an insurer to avoid paying out to third parties (i.e. invalidate the insurance). Clause 148.2(b) of the road traffic act 1988 makes sure of this. The insurer would have to void the policy ab inito , that is literally the only way they can invalidate it, and when that happens the Financial Ombudsman Service heavily favours policyholders over insurers, as an examinations of its ruling will demonstrate. The threshold to void is very high.
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Useful information.

On the other hand, if the policy is comprehensive, they may be able to refuse payment for the policy holder's losses and costs.
 
Well, I can probably end the original discussion as I have found something out. I went to my local tyre dealer today, a friendly and knowledgeable bunch at Smithy's Tyres In Callington. I asked the guy there about using the spare tyre I had and whether or not it would fit the correct sized tyre. He asked me what car I had -- a Skoda -- and asked what car the wheel came from. When I told him it was a FIAT he said that the nut layout between the two makes was completely different and wouldn't fit anyway: And that put paid to that.

He did give the name of a breaker where I could probably get the right wheel and the right tyre in Plymouth so when I come back from holiday I'll contact them.
 
onomatopoeia said:
Once a certificate has been issued, it is very, very hard for an insurer to avoid paying out to third parties (i.e. invalidate the insurance). Clause 148.2(b) of the road traffic act 1988 makes sure of this. The insurer would have to void the policy ab inito , that is literally the only way they can invalidate it, and when that happens the Financial Ombudsman Service heavily favours policyholders over insurers, as an examinations of its ruling will demonstrate. The threshold to void is very high.
Click to expand...

Oh that is interesting! Are there any case law examples floating about to peruse?
 
onomatopoeia said:
Once a certificate has been issued, it is very, very hard for an insurer to avoid paying out to third parties (i.e. invalidate the insurance). Clause 148.2(b) of the road traffic act 1988 makes sure of this. The insurer would have to void the policy ab inito , that is literally the only way they can invalidate it, and when that happens the Financial Ombudsman Service heavily favours policyholders over insurers, as an examinations of its ruling will demonstrate. The threshold to void is very high.
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You understand what third party means, right?

I think it's extremely unlikely an insurer would try to "cancel" insurance because you fitted a slightly different sized tyre for temporary use. But that's nothing to do with the law on third party insurance because you would be the first party. And the laws on first party are significantly different.

Also, the ombudsman can only get involved in contractual issues which since we're taking Latin de iure only exist with the first party.

(And yes, there's a difference between cancelling and voiding but again I don't see the relevance).
 
I had to fit the spare to my last XF and the space saver looked more than a little lost in the arch!
 
Would it not be easier on your peace of mind to have a home fitting done , plenty of firms that do it
 
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