Tyre Speed Rating - Can I go Lower?

vikingaero

EdGasket wrote: »

Yes, good point about winter tyres which are often not available in the higher speed ratings. So what would insurers rather you have fitted in snow/ice; winter tyres with a lower speed rating or summer tyres with the manufacturers recommended speed rating? From what I have researched, it is not illegal to fit a lower speed rated tyre as some have suggested as in the UK you cannot legally exceed 70mph.
Not much use phoning the insurers, I think they would need to agree in writing that it was OK so in the event of a claim they can't wriggle out of it and deny the conversation ever existed. However I am reluctant to contact my insurers as they would probably get the wrong end of the stick and slap on a 'modification' premium or charge me an 'admin fee' for answering my question lol.
On my particular tyres, 175/65 14, there is a much wider choice in T rating than in H. Saving is around £15 per tyre for a better brand dropping to the T.

Despite others telling you the law, you sound so convinced that you are right so do what you think. Just remember to take responsibility for your actions whether that is a fine, voided insurance, ccj for damages because your underrated tyres caused and accident.

flyingscotno1

Many makers specify the wrong rating anyway. My Dad has a 1.9 diesel Octavia- top speed is listed on Parkers and others as 113mph. Should be T rated (I think), yet go to the vehicle reg checkers on many websites they'll recommend the V rated tyres it came with. Now wears H rated tyres which are fine.

On an aside I wonder how many prosecutions ever result from wrong tyre speed rating?

B00st

EdGasket wrote: »

Yes, good point about winter tyres which are often not available in the higher speed ratings. So what would insurers rather you have fitted in snow/ice; winter tyres with a lower speed rating or summer tyres with the manufacturers recommended speed rating? From what I have researched, it is not illegal to fit a lower speed rated tyre as some have suggested as in the UK you cannot legally exceed 70mph.
Not much use phoning the insurers, I think they would need to agree in writing that it was OK so in the event of a claim they can't wriggle out of it and deny the conversation ever existed. However I am reluctant to contact my insurers as they would probably get the wrong end of the stick and slap on a 'modification' premium or charge me an 'admin fee' for answering my question lol.
On my particular tyres, 175/65 14, there is a much wider choice in T rating than in H. Saving is around £15 per tyre for a better brand dropping to the T.

It is quite possible to legally go faster than 70 in the UK, just not on public roads. Also not everyone soley drives in this country.

flyingscotno1 wrote:

Many makers specify the wrong rating anyway. My Dad has a 1.9 diesel Octavia- top speed is listed on Parkers and others as 113mph. Should be T rated (I think), yet go to the vehicle reg checkers on many websites they'll recommend the V rated tyres it came with. Now wears H rated tyres which are fine.

On an aside I wonder how many prosecutions ever result from wrong tyre speed rating?

How do you know that it is the wrong rating? If Skoda have homologated that car against that rating of tyre then that is the one that needs to be used regardless of whether you think that it has too high a speed rating for the car in question. Manufacturers spend an extremely long time testing cars and components, and don't decide on things on a whim when cost of ownership (especially when cars are sold to fleets) is a serious concern.

Lum

What is the maximum design speed of the vehicle? is it the same as the official top speed? Do modifications change it?

For example a VW Golf SDI probably would struggle to do much over 100mph but that same chassis is used in the Golf GTI which is good for much higher than this. Is the "design speed" of the SDI that of it's chassis or it's engine.

My car came from the factory with a speed limiter that makes the engine cut off at 112mph. This has since "fallen off" and the car is capable of a lot more. I run Z rated tyres anyway, but can I still legally run H rated tyres, as I do in winter, because my car was originally designed for a top speed of 112?


I guess stick to what came on the car, or higher, and you're safe (from prosecution). Mine came with H rated tyres so I'm safe even in winter.

paddedjohn

Lum wrote: »

What is the maximum design speed of the vehicle? is it the same as the official top speed? Do modifications change it?

For example a VW Golf SDI probably would struggle to do much over 100mph but that same chassis is used in the Golf GTI which is good for much higher than this. Is the "design speed" of the SDI that of it's chassis or it's engine.

My car came from the factory with a speed limiter that makes the engine cut off at 112mph. This has since "fallen off" and the car is capable of a lot more. I run Z rated tyres anyway, but can I still legally run H rated tyres, as I do in winter, because my car was originally designed for a top speed of 112?


I guess stick to what came on the car, or higher, and you're safe (from prosecution). Mine came with H rated tyres so I'm safe even in winter.

if your top speed is 112mph then you can even fit 'S rated' tyres as this allows for upto 112 mph

adamc260

Assume this

You fit tyres that mean the car can only do.. 90mph but its top speed is 130

You sell it and the new buyer takes it on a private road and wants to take it up to the top speed... but then the tyres burst etc...

The rest of the story is quite obvious

Extreme and might never happen but... could

paddedjohn

i would imagine that would be the new owners problem, its up to you you to check your own vehicle is legal, but what counts as legal on a private road?

flyingscotno1

B00st wrote: »

How do you know that it is the wrong rating? If Skoda have homologated that car against that rating of tyre then that is the one that needs to be used regardless of whether you think that it has too high a speed rating for the car in question. Manufacturers spend an extremely long time testing cars and components, and don't decide on things on a whim when cost of ownership (especially when cars are sold to fleets) is a serious concern.

I kind of meant the online things are specified wrong by the makers (I guess they get the data from there through the DVLA).

My car is wrong too. I get told 205/55 91V online. Manual clearly states 205/55 91H, which is what the car came supplied with. That to me is the correct tyres for the car.

I'm lead to believe the EC formula for speed rating too is Vmax x 5%.

Hammyman

EdGasket wrote: »

So although H rated tyres are specified for my car; what are the consequences of fitting a T-rated instead, other than saving money?

Your insurance company may use it as an excuse not to pay out if it is not the same rating as original manufacturer spec unless you declare it as a mod.

EdGasket

Hammyman wrote: »

Your insurance company may use it as an excuse not to pay out if it is not the same rating as original manufacturer spec unless you declare it as a mod.

They may be able to wriggle out of damage to my own car on a technicality but I didn't think they could avoid the third-party cover to people and their property as well could they?