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Discussion Starter #1
I was just wondering why my tyres are speed rated W
I’ve been told that if I put less than W on, it could invalidate my insurance!
Does anyone know why it’s got a W speed rating when the cars top speed is 122mph.
W is for cars over 160mph.
Is it because it’s all wheel drive?
 

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It's an odd thing. I've never seen a handbook or leaflet for a car that actually specified a speed rating for the tyres. I suspect that the rating on them is simply what the car manufacturer found was cheapest and at least as high as required.
So I'm not sure how putting a lower rating tyre, but obviously higher than the car's top speed (maybe downhill), would be a problem. The insurance thing may be an urban myth even - I've never followed it back.
 

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Discussion Starter #3
The garage I ordered my tyres from (Costco)
Said they were not allowed to fit V. It had to be W because it says so in the tyre plate in the drivers doorwell.
They said insurance would be void if I had a tyre related incident!
But it’s not the insurance I’m bothered about. Just wondered how bmw decided my car should have w
 

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it says so in the tyre plate in the drivers doorwell
Ha. Yes, I didn't think to check there. My Kona has a top speed of 104 and is rated V. Your car is capable of 126, so being a step higher seems reasonable.
I assume they choose the speed by taking the maximum level speed, adding a bit for downhill with a tail-wind, and then adding a safety margin. And then probably pick the next one up ...
 

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I had a look at our Smart car, as that's basically a city car but my other half beats up and down the motorway in it on occasions.
It has narrower tyres at the front and is available with two wheel sizes, so the plate is a little more complex.
But why would one size on one axle need a higher rating? ... :

122490
 

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Discussion Starter #6
I had a look at our Smart car, as that's basically a city car but my other half beats up and down the motorway in it on occasions.
It has narrower tyres at the front and is available with two wheel sizes, so the plate is a little more complex.
But why would one size on one axle need a higher rating? ... :

View attachment 122490
That is a strange one
 

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Surely same reason they get different pressure, the weight distribution is towards the rear, it is possible that there isn’t an H rating in that tyre size, and it would be problematic suggesting a combination which doesn’t exist?
 

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it is possible that there isn’t an H rating in that tyre size,
That would be my guess. But they can't know that an H in that size will never come on the market, so it seems a bit perverse to do it like that - it's a minimum rating after all, not a 'must have this'.

Having a quick google I see a comment that speed is not the only factor in choosing a speed rating for tyres, so there may be other factors at work. That T one is the narrower of the front options, so presumably higher stressed.
 
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