Putting winters on the Mazda soon. Just had a quick look at prices, and there are four different versions of the tyre I want, all same price/size, but different speed ratings (between 110mph to 150mph). Obviously 110mph covers us, but are higher-rated tyres 'better' in any way? Or are slower-rated ones grippier? Or makes no difference?
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Speed ratings on car tyres
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Posted 6 months ago #
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Its not just your top speed, but the acceleration and braking that will determine the speed rating of the tyre, I would check what is recommended for your car, you also need to match the Tyre Load rating.
Posted 6 months ago # -
Nothing to do with acceleration and braking I'm afraid, its based on a standard test where the tyre is run for ten minutes in 6.2mph steps (ten minutes at each step) untill the max speed is reached and the tyre holds together!
The most important thing it to never fit a lower rated tyre than your car was specced with as your insurance complany may have issues with it in the event of an accicdent.
Posted 6 months ago # -
As I understand it, the speed ratings of a tyre must be more than the top speed of the car. As said above if you put on the wrong ones it could invalidate insurance and make the car an MOT failure.
Posted 6 months ago # -
Yeah, you just need to fit the minimum spec recommended by the manufacturer. I've had this argument more than once at a tyre shop -
"You've got to fit the same as what's on there already"
No I don't. I just have to fit what's in the handbook.
It's a sneaky way of amking money, and I've had more then one preson get quite snotty about itPosted 6 months ago # -
Insurance companies will generally be happy to let you drop one speed rating when using winter tyres, because manufacturers' guidance usually says it's fine, though of course you should probably check with them first. Not part of the MOT as I understand. If they're the same price just get the same as what's already on.
Load rating is more important - you shouldn't go lower than the manufacturer's recommended, winter or otherwise.
Posted 6 months ago # -
Like many manufacturing processes, tyre manufacturers don't set up one day to make 150mph tyres and then 110mph tyres the next day.
They all come out of the same moulds, but the ones that are the roundest and the most well-balanced get the higher speed ratings.
Like Intel processors - the ones that actually work get the highest speed ratings.
Posted 6 months ago # -
Insurance companies will generally be happy to let you drop one speed rating when using winter tyres, because manufacturers' guidance usually says it's fine, though of course you should probably check with them first. Not part of the MOT as I understand. If they're the same price just get the same as what's already on.
according to which manufacturer is it fine (tyre? car?)? have you got any links to back that up?
Posted 6 months ago # -
Yeah it's a pain with winter tyres coz you can often get ceaper ones with lower speed ratings.
As I understand it, the speed/load ratings must equal or exceed the recommended ratings for the vehicle or else the insurers may not pay out in the event of a claim.
Posted 6 months ago # -
according to law, the speed rating must exceed what the vehicle will be used for, ergo you could claim any tyre with 'N' or above (88mph - appears to be the lowest rating) is legally fine for any car.
I've heard the 'tale' insurance won't pay out, but unless the tyre fails, or the speed the accident was at was higher than the rating of the tyre, I can't see that they'd be able to (legally). Still, for the sake of a tenner, probably better safe than sorry
Posted 6 months ago # -
5lab - Member
Insurance companies will generally be happy to let you drop one speed rating when using winter tyres, because manufacturers' guidance usually says it's fine, though of course you should probably check with them first. Not part of the MOT as I understand. If they're the same price just get the same as what's already on.
according to which manufacturer is it fine (tyre? car?)? have you got any links to back that up?
the rating for my xc90 is one lower for winter tyres but i would have to scan the handbook to show you.Posted 6 months ago # -
Rocketman if that's the case how do they manage to mould the speed rating into the sidewall without spoiling roundness and balance?
Posted 6 months ago # -
according to which manufacturer is it fine (tyre? car?)? have you got any links to back that up?
Skoda. Octavia VRS. Going from an 225/40 R18 to a 205/55 R16. I did have a link to both a copy of an email from Skoda and a pdf document that listed the approved sizes/ratings but I'm not going searching for them. Buried on Briskoda somewhere if you want to look. It's not 100% but better than guessing and hoping for the best. Getting hard and fast info isn't easy to be honest - the handbook generally doesn't help at all, it's a case of trawling forums and using common sense.Edit - handbook says 'You can fit winter tyres of a lower speed category to your vehicle provided that you also do not drive faster than the permissible maximum speed for such tyres, even if the possible maximum speed of your vehicle is higher.'
Posted 6 months ago # -
Cheers for all the info. I'll check the handbook later as now realise the current ones on there aren't the originals so prob better to check the original spec.
Posted 6 months ago # -
Rocketman if that's the case how do they manage to mould the speed rating into the sidewall without spoiling roundness and balance?
It's when it's written on in felt-tip that you have to worry.
Posted 6 months ago #
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