My car was specced by the original owner with optional 17″ wheels. It takes a 225/45r17 tyre. Speed rating Y which is good for a sustained 186mph.

If the same car was supplied with the standard 16″ wheels it would take 205/55r16 in a V rating, good for 149mph.

Top speed of the car is something like 125mph apparently. Is the higher 17″ speed rating stated as thats a ‘standard’ figure for that size tyre?

I’m looking at some all-season tyres but they ‘only’ go up to a V rating, which would be impossible to exceed unless the car was modified.

I am finding conflicting statements…

It is very important that you check your speed rating before buying tyres. Choosing a tyre with a lower rating than is appropriate for your car can invalidate your insurance.

…in the UK, with a national speed limit of 70 mph, it is quite safe and not illegal to fit a tyre with a lower speed rating, provided you do not exceed this reduced rating

I know you can drop a speed rating for winter tyres, but a Y to a V is two ratings…even though its still well above the capabilities of the car. Are there any examples of an insurance company kicking off due to a tyre that is lower than recommended rating but still comfortably above the capability of the car?

I could ring my insurance but they will almost certainly charge me merely to add a note to the policy! I don’t think they can refuse a claim due to an unrelated discrepancy any more than they? i.e if I neglect to mention I have modified my car with a tow bar (I have) that shouldn’t cause me an issue if I drove it into a wall…

I believe the current perceived wisdom is declare, declare and declare again.

The theory being that although the tow bar wasnt the direct cause of driving into a wall the risk they were insuring was a car without one….so obviously you have a void policy….

I was in this position with winter tyres. I emailed my insurer and they confirmed they were happy. An email is always good.

Don’t they have to show a causal link between an anomaly on the policy and a claim? Maybe just life insurance for that, eg. You neglected to disclose you had high blood pressure then were killed in a plane crash, they can’t wriggle out on that basis any more? Does this apply to car insurance too now?

They’re not conflicting statements; your insurance company should be told if you change the spec / modify your car
Your tyres must be suitable for your vehicle

From experience:
Don’t assume that a lower speed rating will lower the cost of your tyres, you might be asking for something that isn’t a popular choice (a general comment, I get that you’re looking at all-seasons tyres)

^^^An email to my insurers was enough to satisfy them at no charge

V rated tyres are suitable (as they are rated higher than the max speed)…I’m just wondering if the industry ‘standard’ speed rating for a larger low profile tyre that is typically fitted to powerful cars is a Y rating…hence they recommend Y as standard fit, whereas the same car with more a more appropriate tyre size has a lower V recommendation.

I’ll email them. Lets not even get onto the issue of declaring factory options (how many people would know the standard wheel size of their car and whether six years earlier, the original buyer felt a bit flush and paid extra for some bigger wheels and/or colour matched bumpers?!) I know we didn’t declare them on the basis we wouldn’t reasonably know, and that most insurance companies would just put us in the boy racer category and load the policy as the car is ‘modified’.

If you downgrade to a lower speed rating you must tell your insurance company in writing. If they can find any excuse not to pay on a claim they will. Winter tyres are an exception to this rule as you are not expected to drive at high speed in wintery weather.

It’s not al about the maximum speed a car can go, cars restricted to 130mph but have a higher speed rated tyre, but also to do with the amount of torque the engine has.

If you downgrade to a lower speed rating you must tell your insurance company in writing. If they can find any excuse not to pay on a claim they will.

They would need to show that the change had a material impact on the cause of the crash otherwise they’d lose if you appealed.

Also check the load rating, this is irrelevant of speed rating.

From wiki:

In many countries, the law requires that tires must be specified, and fitted, to exceed the maximum speed of the vehicle they are mounted on, with regards to their speed rating code (except for “temporary-use” spare tires). In some parts of the European Union, tires that are not fit for a car’s or motorcycle’s particular maximum speed are illegal to mount. The sole exception are M+S tires, where a warning sticker stating the allowed maximum speed must be placed within clear sight of the driver inside the vehicle. Some manufacturers will install a speed governor if a vehicle is ordered with tires rated below the vehicle’s maximum speed. In some parts of the European Union, e.g. Germany, it is allowed to mount tires with a lower speed rating code if the car manufacturer specifies tires with a very high speed rating in the registration documents and the vehicle will not reach this speed based on insufficient power.[14] In this case it is possible to calculate the appropriate speed rating with a formula.[15]

I think you will find most car tyres have M+S markings. It’s to do with certain markets requiring all-season tyres during colder months. Simply marking a tyre as M+S is enough even though it is not a winter specific tyre tread or compound.

You don’t see many standard (i.e summer) tyres marked as M&S…and most drivers still use summer tyres despite being dire in snow and performance dropping off a cliff in cold conditions. A good proportion of all season/winters will be M&S though.

Er, yes they are. They are marked with M+S but not considered to be a winter tyre. Step outside and take a close look at your car tyres