Speed ratings on tyres
Discussion
Kawasicki said:
Pontoneer said:
Hooli said:
On some cars higher rated tyres are fitted because the stronger structure allows higher cornering loads rather than just a higher top speed.
Exactly , the load rating is not just to do with the static weight of the car which sits on each corner , but is also to do with the dynamic loading generated when accelerating , braking and cornering , hence higher performance cars can require a higher load rating and can be at risk if inadequate tyres are fitted , even though the maximum speed for the tyre is never exceeded .Presumably load ratings are just tested in a similar fashion. And somewhere along the line there is a minimum load rating and speed rating for a particular size tyre set by the governing body.
Surely cars like Caterhams whose tyres are generating huge forces through acceleration and cornering would be running Y rated tyres if you apply the above logic , but from what I can find out they run V rated in 13" even on their top spec models .(Googled Avon CR500)
scorcher said:
Kawasicki said:
Pontoneer said:
Hooli said:
On some cars higher rated tyres are fitted because the stronger structure allows higher cornering loads rather than just a higher top speed.
Exactly , the load rating is not just to do with the static weight of the car which sits on each corner , but is also to do with the dynamic loading generated when accelerating , braking and cornering , hence higher performance cars can require a higher load rating and can be at risk if inadequate tyres are fitted , even though the maximum speed for the tyre is never exceeded .Presumably load ratings are just tested in a similar fashion. And somewhere along the line there is a minimum load rating and speed rating for a particular size tyre set by the governing body.
Surely cars like Caterhams whose tyres are generating huge forces through acceleration and cornering would be running Y rated tyres if you apply the above logic , but from what I can find out they run V rated in 13" even on their top spec models .(Googled Avon CR500)
Let me clarify;
To determine the correct load rating for a tyre you just need axle loads, as in the loads when you put the vehicle on a set of scales. It has nothing to do with how hard the vehicle will corner or brake. Similarly speed index requirement is determined from the speed the vehicle will travel in a straight line, nothing to do with how hard the car will be driven.
lbc said:
This^^
Insurance company will only be interested if tyres are a different size to standard, or fitted on more expensive alloy wheels than standard.
I have asked insurers before, and they are not interested in speed ratings.
If speed rating was an issue, then all winter tyres would be banned!
Flipside I have come across one or two that do (or used to) care and you would get it listed as a modification as it is usually either anything above standard specification (UKI Limited mostly - this includes declaring any factory fitted options something many do not think about) or changes made after it was new/first registered...so yes by changing the speed rating you (taking it categorically to the letter of the contract) change the basis on which the insurer offered to provide cover for you.Insurance company will only be interested if tyres are a different size to standard, or fitted on more expensive alloy wheels than standard.
I have asked insurers before, and they are not interested in speed ratings.
If speed rating was an issue, then all winter tyres would be banned!
Whether they care about the change is entirely up to their viewpoint.
In regards to Winter Tyres this did cause issues in 2010/11, however with the ABI stepping in with the Winter Tyre Commitment this changed for many to being a position of no modification but only for winter wheels and tyres....
scorcher said:
Surely cars like Caterhams whose tyres are generating huge forces through acceleration and cornering would be running Y rated tyres if you apply the above logic , but from what I can find out they run V rated in 13" even on their top spec models .(Googled Avon CR500)
Cars like Caterhams do not generate huge forces through acceleration and cornering.Acceleration forces will be more or less the same for a given engine power, irrespective of the mass of the vehicle. Remember that force = mass x acceleration. If two cars are otherwise identical, and one is given twice the mass with sandbags, the acceleration will be half that of the less massive car. But the acceleration forces on the tyres will be exactly the same.
The same is not true for cornering forces, where for a given corner radius and cornering speed, the car with twice as much mass will apply twice the cornering force on the tyres (assuming that both cars are within their limits of grip). In reality, a light car like a Caterham will get through a bend more quickly than a heavier car, but likely not so much faster that the cornering forces will be the same as for the heavier car.
So in effect, light cars like Caterhams generate lower tyres forces than heavy cars like Bentleys.
Ninja59 said:
Flipside I have come across one or two that do (or used to) care and you would get it listed as a modification as it is usually either anything above standard specification (UKI Limited mostly - this includes declaring any factory fitted options something many do not think about) or changes made after it was new/first registered...so yes by changing the speed rating you (taking it categorically to the letter of the contract) change the basis on which the insurer offered to provide cover for you.
Whether they care about the change is entirely up to their viewpoint.
In regards to Winter Tyres this did cause issues in 2010/11, however with the ABI stepping in with the Winter Tyre Commitment this changed for many to being a position of no modification but only for winter wheels and tyres....
Insurers care about wheels not tyres. Whether they care about the change is entirely up to their viewpoint.
In regards to Winter Tyres this did cause issues in 2010/11, however with the ABI stepping in with the Winter Tyre Commitment this changed for many to being a position of no modification but only for winter wheels and tyres....
The ABI is a trade body. It can't "step in", it releases stuff that the industry wants it to release to cover it as a whole, rather than individual companies releasing loads of press snippets.
Winter tyres, just like windscreen wipers and dust caps are not and never have been an issue, other than for pedants on websites to get for they about.
Has anyone spotted how old this thread is?
snorky782 said:
Insurers care about wheels not tyres.
The ABI is a trade body. It can't "step in", it releases stuff that the industry wants it to release to cover it as a whole, rather than individual companies releasing loads of press snippets.
Winter tyres, just like windscreen wipers and dust caps are not and never have been an issue, other than for pedants on websites to get for they about.
Has anyone spotted how old this thread is?
So why then do I have years of previous history having spoken to underwriters for my own car where tyres were an issue (changing anything about size, load rating or speed rating was a modification...).The ABI is a trade body. It can't "step in", it releases stuff that the industry wants it to release to cover it as a whole, rather than individual companies releasing loads of press snippets.
Winter tyres, just like windscreen wipers and dust caps are not and never have been an issue, other than for pedants on websites to get for they about.
Has anyone spotted how old this thread is?
Furthermore, whether you like it or not changing any of them is a modification to the overall car from it's original specification (whether that be options or after first registration).
Ninja59 said:
So why then do I have years of previous history having spoken to underwriters for my own car where tyres were an issue (changing anything about size, load rating or speed rating was a modification...).
Presumably because you chose to? I will wager that many people don't. Ninja59 said:
Furthermore, whether you like it or not changing any of them is a modification to the overall car from it's original specification (whether that be options or after first registration).
Every owner's handbook I have ever seen gives the OEM tyre size and pressure together with the load/speed rating.However, I really can't see why an insurer would be concerned if tyres with a higher load/speed rating were to be fitted.
Lower is something else.
In my case, I fitted bigger (diameter) aftermarket alloys because the choice of tyres for the OEM sized wheels is now very limited.
Mostly Chinese budget tat and I don't want to end up in hedge/ditch. Of course I declared the change (along with a substantial list of other items).
Ninja59 said:
snorky782 said:
Insurers care about wheels not tyres.
The ABI is a trade body. It can't "step in", it releases stuff that the industry wants it to release to cover it as a whole, rather than individual companies releasing loads of press snippets.
Winter tyres, just like windscreen wipers and dust caps are not and never have been an issue, other than for pedants on websites to get for they about.
Has anyone spotted how old this thread is?
So why then do I have years of previous history having spoken to underwriters for my own car where tyres were an issue (changing anything about size, load rating or speed rating was a modification...).The ABI is a trade body. It can't "step in", it releases stuff that the industry wants it to release to cover it as a whole, rather than individual companies releasing loads of press snippets.
Winter tyres, just like windscreen wipers and dust caps are not and never have been an issue, other than for pedants on websites to get for they about.
Has anyone spotted how old this thread is?
Furthermore, whether you like it or not changing any of them is a modification to the overall car from it's original specification (whether that be options or after first registration).
No comment about your ABI "stepping in" opinion?
Red Devil said:
Every owner's handbook I have ever seen gives the OEM tyre size and pressure together with the load/speed rating.
However, I really can't see why an insurer would be concerned if tyres with a higher load/speed rating were to be fitted.
Lower is something else.
In my case, I fitted bigger (diameter) aftermarket alloys because the choice of tyres for the OEM sized wheels is now very limited.
Mostly Chinese budget tat and I don't want to end up in hedge/ditch. Of course I declared the change (along with a substantial list of other items).
Because I choose to? Or because I realised that it would be altering the car from the cars original factory specification and therefore contract and good faith upon which it was originally based. Whether or not I decided to go ahead with the change is irrelevant. However, I really can't see why an insurer would be concerned if tyres with a higher load/speed rating were to be fitted.
Lower is something else.
In my case, I fitted bigger (diameter) aftermarket alloys because the choice of tyres for the OEM sized wheels is now very limited.
Mostly Chinese budget tat and I don't want to end up in hedge/ditch. Of course I declared the change (along with a substantial list of other items).
OEM handbook is irrelevant it is decided on what the car originally came fitted with (size, speed and load rating).
snorky782 said:
As said above, presumably because you wanted to. I fit 200 tyres to my bikes now instead of 190s, never disclosed it and I know it won't cause an issue.
No comment about your ABI "stepping in" opinion?
Take your risk yourself personally, being of upmost good faith I would prefer to declare and let them decide whether it is relevant or not....far better than finding out down the line, finding out that they would need to know and being in a fight with your insurer (and if you outlast their complaints side the Insurance Ombudsman).No comment about your ABI "stepping in" opinion?
Furthermore I would like to "know" how you know if you have not even bothered to communicate with them...
Or to put it in a simple way a few minute phonecall going yes, no and whether you proceed v hours of stress and additional costs with potential uncertainty...
Matter of phrasing...overall the result was the Winter Tyre Commitment.
Edited by Ninja59 on Tuesday 24th May 15:29
My car has 4x V rated tyres. Three need replacing.
I have a good deal on some tyres which are W rated, which I know are 'better' than V tyres.
Will I have any issues with three W and one V tyres on the car...?
(V is more than enough for the car. Common sense tells me the above shouldn't be a problem but.....)
Thanks.
I have a good deal on some tyres which are W rated, which I know are 'better' than V tyres.
Will I have any issues with three W and one V tyres on the car...?
(V is more than enough for the car. Common sense tells me the above shouldn't be a problem but.....)
Thanks.
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