TyreSpeed - Rick Laughton
Unfortunately 1 of the front tyres on my Alfa 156 2.0TS has punctured. As it had covered 27,000 miles, I decided to replace rather than attempt a repair. As the other front tyre is quite worn as well (having also covered 27,000 miles) I decided to repalce 2. I was quoted £112 each for Michelin 185/55V15 - the same as the existing tyres.

For a lower speed but otherwise identical tyre (a Michelin 185/65H15) I was quoted £68 each. I don't know a huge amount about tyre speeds - but a litle research ahs told me that V are rated to a maximum speed of 150 mph, and H upto 130 mph. I can understsand that one should probably not mix different speed tyres, but is there anything wrong with buying two new H rated tyres rather than the V. I never touch 100 mph, never mind 130 or 150!?
Re: TyreSpeed - sam
the £68 tyre you mention is different to the one with the v speed rating as it has a higher profile. putting the cheaper tyre on will have the effect of increasing the diameter of the wheel/tyre combo, and thus your speedo and gearing will be affected, not mentioning the fact that the extra diameter could cause fouling.

part of the price discrepancy will undoubtably be as a result of the different speed ratings, but in this instance also because of the different profiles.

i wouldn't decrease the speed ratings, but i'm no tyre expert.
Re: TyreSpeed - Robert Harvey
Sam,

Can you expand on what you mean by fouling please.

Thanks ........

Robert
Re: TyreSpeed - Michael
Rick, I think you understand the issue quite well. I think it is safe as long as you keep matching pairs per axle. You will have to be mindful as and when you use your spare tyre that you do not end up with a wrong combination in the future. Incidentally, don't forget that the tyres with most tread should be on the rear, regardless of whether it is a front or rear wheel drive car.
I was once told that insurance companies should be told if you effectively change the spec of a car, but would have thought this would be ok though, as long as you don't plan a 150mph blast on the autobahn.
Re: TyreSpeed - Michael
ps, the v and h ratings have no bearing on profile or diameter, just the compound that the tyre is made of.
Re: TyreSpeed - Mark (Brazil)
Michelin 185/55V15
Michelin 185/65H15

one showing 65 and the other 55. Could have been a typo, I suppose.
Re: Handling changes. - Tim Allcott
Can someone explain why most tread has to be on the rear tyres?
The only way I can get the back to break away on my Passat is by doing handbrake turns on fresh snow in a (private) car park.
I suppose I could do it in the dry too, but the tyres wouldn't last long.
I'm just about to replace two rear tyres, and would normally put the new ones on the front, and the part worn on the rear
Re: TyreSpeed - Michael
well spotted Mark, trust me to read the words ("..For a lower speed but otherwise identical tyre.." ) and ignore the numbers.

Rick, please clarify.
Re: TyreSpeed - Rick Laughton
Gentlemen

Apologies for the misleading information! I should have typed: -

Michelin 185/65V15 at £112 each
Michelin 185/65H15 at £68 each

i.e. identical other than the letter representing the speed!
Handling changes. - David Woollard
I've got to say faced with that dilemma on my own car I did the same. With mine it was a 185/65x14HR which I decided to downgrade on cost basis to the same sized Michelin but in an SR rating.

When the tyres were fitted it was obvious the sidewall shape and tread contact patch was different. Also that made me think more about the different handling characteristics of the HR vs SR rubber compounds. What about a possible difference in wet road grip?

So within a couple of weeks I took off the SRs and found matching HRs to my existing ones. Otherwise I would have been many months with this front to rear mismatch.

The insurance question was another worry, as one of you said. I do think, in the event of a claim, this issue could be looked at by a vehicle examiner.

David
Re: Handling changes. - Andy Bairsto
new vehicles are issued with and typecast with a size and speed rating,this lives with the car forever .Fitting tyres with lower rating than specified is against the law ,in the event of an accident a smart eyed insurance assessor would soon spot any anomily .The rest of europe checks tyres at mot time and the police check in roadside safety inspections.If you have wrong tyres in france or germany and holland your car stays where it is until you change them.The correct rating is fitted by the manufacturer for your own protection but in a country with a 70mph speed limit all cars good probably run on remoulds quite safely.Certain all wheel drive motors such as older volvos and audis you have to change all the tyres as the difference in diameter causes the diffs to disintergrate .I personnaly think cheap safety articles are false economy
Re: TyreSpeed - Andrew Smith
Find the manufacturers listed top speed for your car. If this is below 130 mph then you can fit H rated tyres. I don't know the alfa 156 2.0ts but it's probably 130 something.
As far as I know the only requirement is that you have tyres fitted which have a speed rating in excess of the top speed of your vehicle. This is an MOT requirement. Whether it ever gets checked is another matter.

My car was fitted with W rated Michellin Pilots from new (170mph). By the time I bought it (from a main dealer) two of these had been replaced with V rated tyres. These have been on both the front and back of the car I can observe no difference between them (other than about £50 a corner) even at 149 mph ;-)
Re: Handling changes. - Rick Laughton
I agree with your attitude towards safety - I do not wish to economise on that. However, if a tyre is rated up to 130 mph - how can that be unsafe if I never approoach it?

In addition, how do foreign police forces check for correct tyres. Even Alfa Romeo cannot agree - my car being sourced from Holland came with 185/65V15 tyres - however, the same car sourced in the UK came (so I am told) with 205/60V15 tyres. I can get these for £65 each - and thus replace all 4 tyres for a little more than just the 2 with 185/65V15 at £112 each! Which of these would be the safest option?
Re: Handling changes. - Andy Bairsto
the size is stamped in all european log books ,sometimes there are two options and these are both printed there .The police have in there computor in every car the data base plus you must always carry your log book with you.I agree that the ratings as I have said are ridiculous for the UK but they exist are have to be obeyed.The options you quoted have both "V" ratings that is the important part.
Re: Handling changes. - Jonathan
Is this correct?

What if you own a car that doesn't have a log book?

Surely you must carry the V5 (or equivalent) and not the log book (service history only).

Puzzled.

Jonathan
V5 - John Slaughter
Jonathan

No, you don't have to carry the V5. If it's a company car you won't have it anyway. What you then carry is a standard form from the lease company giving you permission to take the car abroad.

regards

John
Re: TyreSpeed - Rick Laughton
216 kmh which is about 134mph - so I guess that means the Vs!

With that decided (!?) can anyone tell me a cheaper source of decent 185/65V15s - South Manchester!!!??
Re: TyreSpeed - Jonathan
Yes

I use E&D tyres

they are in Handforth/Wilmslow, behind the Ferrari and Maserati garage. They are the cheapest ones that i know of,

Regards

Jonathan
Re: TyreSpeed - Jonathan
E & D Motors Deanway Trad Est Wilmslow Rd, Handforth, Wilmslow (01625) 536299
E & D Motors
204 Wilmslow Rd, Heald Green (0161) 498 8498
204 Wilmslow Rd, Heald Green (0161) 498 9595
Re: Handling changes. - Rick Laughton
So is it OK to put 205/60V15s instead of 185/65V15s?
Many thanks
Re: Handling changes. - sam
i'd have thought it would be alright provided the rims are wide enough and the aspect ratio of the tyre is kept reasonable.
Re: Handling changes. - steve paterson
Andrew Smith say's that tyre speed rating is part of the MOT. Unless things have changed recently, it isn't. When I was MOT testing (few years ago) you could fit four cross ply remoulds to your Ferrari, and the spare could be anything as it wasn't a testable item. Manufacturers recommendations and Construction and use regs. aren't always part of the MOT.
Re: Handling changes. - Andrew Smith
Oh. I stand corrected. Why then do we not just go out and buy lower rated tyres for our cars.
Experience seems to suggest that lower rated tyres have softer compounds and consequently more grip. My aformentioned W rated Pilots were some of the worst gripping tyres I've ever experienced on a car, transmitting every shock back through the steering wheel and losing traction over the smallest bump. I confess they cleaned up above about 110 mph but I don't go that fast very often.
Re: Handling changes. - Michael
Tim, regarding best tyres going on the rear, this was always the case with rear wheel drive cars (the driven wheels being on the back) but there was a widespread belief that on fwd cars the best tyres should be on the front. Last year, the beloved Top Gear showed a demonstration of the effects of various tyre combinations on fwd cars, and, in adverse conditions, the rear of the car started to slide in the same way that a rwd would. It apeared to be a matter of stability. The point was made to me by a driving instructor that the rear will try and overtake the front because the tyres on the back have less grip than the front, again under adverse conditions such as heavy braking or hard cornering or slippery road conditions. It was also apparent that a rwd with rear end slide is more controllable because you can influence the behaviour of the rear wheels with the accelerator, gears, clutch and brake. With a fwd, rear wheel slide, it is more difficult to control as the only thing at your comand is the brake.
Re: TyreSpeed - richard turpin
Many years ago I had an Austin A40. I put the then new Michelin X low profile tyres on the front and high profile cross plies on the rear. I drove many thousands of miles all over europe (there were few motorways) oversteering at low speeds all the time. It weas great fun and I never had an accident.

Recently I got some 70 profile tyres for my Previa instead of the 65 profile as supplied. I put them on the rear with the originals on the front and it wandered all over the place. I changed them round and the car was very stable. The answer is that high/low profile makes a huge difference. Low profile has much better grip but is easily destroyed by kerbing in town. High profile has worse grip but can cope with kerbs/bumps. Put the worse grip tyres on the front and you will understeer safely. Other way round, have fun but be very awake and take the speed easy.
Re: TyreSpeed - Vin
Rick,

The motorbike magazines on this subject say that the ratimg reflects the ability the tyre has to handle the power being put through it, not just the speed at which it rotates. Top speed is probably as good an approximation of power output as you can reasonably get, hence tyres are "speed rated" even though they should be "power rated". A 150mph car obviously puts more power through the tyre than a 100mph car, hence its higher rating. The build, construction and tyre compound will be different for different speed ratings, which accounts for a chunk of the price gap; the rest of the gap is probably down to cynicism.

Putting the wrong spec tyre will definitely invalidate your insurance.

Vin
Re: TyreSpeed - Michael
Richard, one of the differences between high and low profile tyres is the diameter and consequently the circumference of the tyre. A combination of high on the front and low on the back means bigger wheels on the front and smaller on the rear or vice versa if you change them round. It also affects the accuracy of the speedometer, smaller diameter tyres = speedo reading fast, larger diameter wheels = speedo reading slow and potentially damaging to your license and pocket as you could be travelling at 40mph when your speedo says 30mph.
Re: Handling changes. - Rick Laughton
Jonathan

Many thanks - they have sorted me out at a considerable saving!
Re: Handling changes. - Jonathan
really?

Great news

Glad to be of help

Incidentally, how much?

Jonathan
Re: Handling changes. - Rick Laughton
I opted for some Firestones (which were about £92 all in at the previous place) for £56 + VAT!
Re: TyreSpeed - John Slaughter
Rick

Don't do it. The issue is not one of whether you actually reach 150 miles/hr. The fact is your car has the potential and power to do so. It also has the brakes and suspension to handle the power and the speed. So, the tyres have to be capable of handling the power output, acceleration and cornering capability etc of the car, and that's what you pay for with the VR tyre.

As other have pointed out, fitting the 'wrong' tyres can be a get out for insurers, and as Andy B says, in germany it's actually illegal to vary the spec of the car that way.

Regards

John
 

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