This all sounds very impressive but to justify what you claim, could you point me to the specific regulation that refers to using temporary use spare tyres (to give them their proper name) within prescribed diameter limits, in an emergency and the application of speed limits when using them? Clearly temporary use spare tyres, with a speed rating of M, wouldn’t meet the manufacturer's specification for regular tyres but they do seem to have a high load rating.

Your handbook gives the conditions for the use of a spacesaver, these are extracted from the Conditions of Use regulations regarding motor vehicles, which contains many appendices to many sections, just accept that there are limitations on mixed tyres of a similar diameter within specified limits on the same axle. my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

In other words, you have absolutely no idea of what the legal position is so you just throw out a lot of meaningless nonsense.

Thanks

I think you are over thinking this. Car manufacturers spend millions of pounds developing and type approving cars and components including spare wheels, space savers or otherwise.
I'm sure their use is perfectly legal. Landrover - turning owners into mechanics since 1948

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Simon J wrote:

In other words, you have absolutely no idea of what the legal position is so you just throw out a lot of meaningless nonsense.

Thanks

I’m just curious as to how something can be legal, i.e. different sized tires, yet be an instant MOT failure.

Sidthecat wrote:

Simon J wrote:

In other words, you have absolutely no idea of what the legal position is so you just throw out a lot of meaningless nonsense.

Thanks

Perhaps if you’re going to take this attitude when everyone’s trying to help, you’d best go away and research the answer yourself

https://www.legislation.gov.uk/uksi/1986/1078/regulation/25/made
https://www.legislation.gov.uk/uksi/1986/1078/regulation/26/made
https://www.legislation.gov.uk/uksi/1986/1078/regulation/27/made
https://www.gov.uk/guidance/mot-inspection...suspension
The above cover the legalities, though you do need some technical knowledge to de-cypher the wording, basically it is in line with that I posted. It didn't take that long, perhaps you just don't understand the wording. my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

I already read those regs and they refer to the construction of tyres with a derogation for temporary use spare tyres. Nothing to do with different sizes.

Then you are not reading it correctly, it states what is legal on each axle, read the MOT rules on sizes and defects, the MOT defines a legal vehicle, if you drive a vehicle that is not within the MOT criteria then it's illegal, irrespective of whether or not it has a test certificate. my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

But this still doesn’t explain how a tyre can be an MOT failure - which a space saver would be - and yet still be considered legal to use. I can’t find a derogation relating to size similar to the one in reg 26 for temporary use spare tyres which can be of a different construction to the other tyre on the axle.

It's really quite simple, the space saver is a temporary wheel and tyre, you can't have an MOT on a temporary fitting, the car must be fitted with all its standard equipment in a safe condition including extras if fitted, the space saver is not a standard fitting it is a temporary fitting and cannot be included in the test.
Your spare being of the same overall diameter as the fitted ones would be treated as a space saver and limited to space saver restrictions but won't pass an MOT for the same reason as a space saver. my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

wouldn`t two odd size tyres over work the diff like going around a corner permanently or am i over thinking it  2009 FL2 S now gone
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Simon J wrote:

In other words, you have absolutely no idea of what the legal position is so you just throw out a lot of meaningless nonsense.

Thanks

robblue wrote:

wouldn`t two odd size tyres over work the diff like going around a corner permanently or am i over thinking it