It seems to be an accepted fact that you shouldn’t have different sizes of tyres on the same axle and it is, I understand, an automatic MOT failure if a vehicle is presented with mis-matched tyres on the same axle.

But could anyone point me to the specific regulation that prohibits this, or is it simply an MOT matter?

I hasten to add that I’m not planning to have odd sized tyres on my FL2 but I did notice that the spare wheel - which seems to be an unused original item - has a tyre size that’s completely different to the tyres on the road wheels. It’s not a skinny space saver; it’s a 225/65 R17 102H.

I can't help on your MOT issues.


The different spare wheel even if it has the same diameter most likely has a 100km range in the fine print. Procrastination, mankind's greatest labour saving device!

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Thanks, but it isn’t an MOT question, nor is it about how far you can drive on the spare; it’s about the actual legislation that applies, if any.

According to the AA there is no law.

https://www.theaa.com/driving-advice/safet...are-wheels FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 76k+ miles) (MY2015)

Thanks, but they say “ Tyres on the same axle must be of the same size and aspect ratio” but without explaining 'must'. Can you be a bit more specific as I don’t immediately see your reference?

Simon J wrote:

Thanks, but it isn’t an MOT question, nor is it about how far you can drive on the spare; it’s about the actual legislation that applies, if any.

Thanks, but I should have said that I’ve already been through the C&U Regs but to no avail - hence my question.

Reading the regulations as there is nothing there you could clearly argue the point with MOT! Procrastination, mankind's greatest labour saving device!

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Would that then not point to the fact that there is no legislation as such & it is just an MOT requirement.

Have you looked at the MOT testers manual to see what is actually specified? (Now Sold). 2008 Freelander 2 (Nazca Sand) SE TD4 Auto. Statutory write off & on WOVR for hail damage but still road legal.
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If MOT is not following the legislation it is probably worth arguing, but you may need a conga line of barristers.

Maybe cheaper to have the same wheels everywhere. Procrastination, mankind's greatest labour saving device!

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Two different tyre sizes on the same axle is just classed as a major defect but with no explanation.

C&U and MOT rules are often not the same. For example you could attach a load of knives to the front of a car and be prosecuted under the C&U act but you can only fail sharp edges on an MOT test if they are caused by corrosion or accident damage. Oh, and the only different sizes of tyres you can have on the same axle for an mot test are 80 aspect tyres and unmarked aspect tyres which are 82% but are classed as near enough! Past: FL2 TD4 HSE Auto
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Yes, I’d noticed that about what they call 'standard' tyres.

My reason for asking was to try and determine how skinny 'space saver' tyres can be used if they would constitute an MOT fail if fitted for the test. I had thought there might be some exemption for them, as there is for their type of construction, i.e. they don’t have to be of the same construction as the other tyre on the axle provided they’re driven at less than 50 mph, but seemingly not. So it’s not illegal to mix tyre sizes but you’ll fail your MOT with them!

What a peculiar situation. Even if there isn't a law, surely there's a published regulation.

Of course it may be that the MOT requirements are covered by another reg or legislation.

Much clearer down here. Unless you're going through an engineering process. MY11 SD4 SE Auto

You can have any tyre on the same axle in an emergency providing it is within the prescribed diameter limits (see uses of temporary space saver tyres ) though you will have a speed limit irrespective of the tyre's marked specifications, however the tyre must conform or exceed the weight and speed to the vehicle which it is fitted, i.e you can't fit a lawn tractor tyre or Buggy tyre to a car, the weight limits and speed are below that of the published specifications of the vehicle.
Regarding the MOT, this certifies that the car is inroad worthy condition and is at the time fit for normal use, the fitting of any tyre of a specification below that of the requirements for normal use is a failure, see tyres fitted on the same axle.
The problem with technical regulations is that they are altered with provisos and appendices which are not always apparent in the laws or rules you are searching, but because you can't find them someone else can an will use them against you. my PC is slightly to the right of Genghis
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