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Cleaning Mrs car this PM noticed that the Continental Sport Contacts are V rated.Anybody know why Vx would fit these as standard, the cars a 2.0 DTI with 205/55/16 alloys and i doubt if it would do over 110.Surely H rated tyres would suffice?
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I had this with a company leased Mondeo, and Ford had issued a bulletin saying it was OK to fit the lower speed rated tyres.
What does the handbook, or other tyre data label on the car say? You have to be a little bit careful, because if the car was type approved with those tyres then there could be insurance issues if you derate them. You may find there isn't much, or even any, difference in they tyre price - some of the online tyre places offer you higher speed options at the same price. I would imagine in many cases the tyres are identical, but simply have different markings.
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Don't mess with tyres. The specification determined by the manufacturer is crucial. Speed is only one of many factors on which it is based. "DTI" indicates diesel, yes? So there's a lot of torque and probably a weighty engine too, for a start.
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I raised this subject some time ago, as our C5 had W rated tyres fitted. I suspect that this is because they are the same wheels that are fitted to the 3.0 V6 version. Ours is an Exclusive model with the 2.2 HDI engine but the SX version, with the same engine but different wheels, had H rated tyres fitted.
The speed rating has nothing with load, which has a separate rating, so the weight of the car and torque of the engine are, I believe, not relevant to the speed rating. After all, the same engine that is in the C5 can be found in the C8, which is a much heavier vehicle, albeit slower too, and these are fitted with H rated tyres. The load rating of the tyres on a C8 is, however, higher than for a C5.
When replacing the rear tyres on our C5, I contacted my insurers to check that a lower rating would suffice and I was told that as long as they had a rating in excess of the top speed of the car, it would be OK. I have had H rated tyres on the rear wheels now for some time, with no problems whatsoever. There is no chance of me getting near to the top speed of the car in any case.
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I have just checked on the Michelin site and the standard tyre recommended for a C5 2.2 HDI, with 15 inch wheels, is H or V rated.
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Thanks,
appears from googling that top speed is 109, believe that as it is Ltd edition model (Energy) VX fitted whatever was available @ the time.
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In that case, H rated tyres are more than adequate.
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In Germany and many Eu lands the tyre specs are printed in the log book if you put anything with a lower spec it will not pass the TUV and leaves you open to a hefty fine and the vehicle empounded till they are changed.The police have access to a data base of every vehicle and often see it as a quick way of upping their figures.
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Are you allowed to go up speed ratings without problems? e.g. T to H etc etc.
cheers
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"The speed rating has nothing with load, which has a separate rating, so the weight of the car and torque of the engine are, I believe, not relevant to the speed rating."
Machika, you may well be right, and I'm no expert, but I'm not sure that you are and I've seen plenty of postings by people who are puzzled that the speed rating of their tyres seems to exceed the maximum speed of their cars by some margin. However, I am more confident about the need to stick to what is specified in the handbook.
Using tyres with speed ratings higher than those recommended by the car manufacturer does of course waste money, as tyres with higher speed ratings tend to be more expensive.
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Don't mess with tyres. The specification determined by the manufacturer is crucial.
Good advice, because even putting aside speed and load ratings, some makes of tyre do not suit certain suspension set-ups, and may cause annoyances like 'tramlining'on motorways, which is perhaps not dangerous but spoils the feel of the car.
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It may well be that the manufacturer bulk buys a couple of hundred thousand tyres and all models, slow and powerful get the same tyre. Over specing never upset customers. Do H tyres have a better ride than V tyres?
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Whatever is in the handbook has to be legally watertight. I would be very surprised if any manufacturer failed to specify precisely the correct tyre for a particular vehicle. Imagine the law case based on "the accident occurred specifically because the wrong tyres were fitted when the car was manufactured and it has also since emerged that the vehicle handbook contains incorrect information in this respect".
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I agree with MW, the car manufacturer probably "Rationalises Inventory" and just keeps one tyre that will suit many applications. I also wonder if the tyre manufacturer bothers to make that tyre and size in a lower rating? There seems to be little financial sense in setting up production and warehousing for two tyres which are probably 99% identical save for another layer of nylon cord or whatever costing about 20p.
My size of tyre 225 55 16 is only available in V or higher, yet is fitted to some base model vehicles which do about 115mph flat out which means an H or T would suffice.
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Whatever is in the handbook has to be legally watertight. I would be very surprised if any manufacturer failed to specify precisely the correct tyre for a particular vehicle.
The Vauxhall manuals I've read don't give specific tyre ratings for specific versions of the model, just a variety of tyre types & recommended pressures.
I sususpect, as others have stated, that the tyres fitted have more to do with minimising inventory than safety, within reason of course.
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I have quoted what the Michelin site recommended for a C5 2.2 HDI. The SX 2.2 HDI is mechanically identical to an Exclusive, the only difference being the size of the wheels (and therefore the tyres) that were fitted. The SX had 15 inch wheels and the Exclusive had 16 inch wheels, the same as fitted to the 3.0 V6.
I have no reason to doubt the advice given by Michelin for their own tyres.
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It may well be that the manufacturer bulk buys a couple of hundred thousand tyres and all models, slow and powerful get the same tyre. Over specing never upset customers. Do H tyres have a better ride than V tyres?
You wouldn't know there was any difference with our C5. The H rated Continentals on the back give a very comfortable and quiet ride. The car's handling has not been affected adversely either.
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