Rubber on the Front..
Discussion
I have just been on the phone to my insurers (Sunninghill) on this and their view was it has no effect whatsoever on insurance.
I have asked them to contact the underwriters to confirm.
Have also had a look at the MOT regs on this and it only says something along the lines of must be suitable for purpose. Does not specifically mention speed rating.
I'm not disagreeing with Steve on this, but Steve - won't most of the accelerative forces go through the rear tyres? I would have thought braking put more stress on the front tyres?
That aside, it does seem weird that they use the same technology/construction methods for the front and rear tyre, but one is V and the other Z. Presumably, if you could, you'd get the highest rating available to the tyre? So the inference is that the front tyre is genuinely not as robust as the rear.
Whilst typing Sunninghill have called back to say that the underwriters confirmed that there is no issue using V rated tyres on the car as regards invalidating insurance and have made a note on my policy details that I am using them.
I did point out that I am not actually using them - I have Z rated S02's on the car which have a lot of life left in them.
Insurance wise it really isn't as clear cut as people make out.
That said, I would still be in two minds about using them!!
I have asked them to contact the underwriters to confirm.
Have also had a look at the MOT regs on this and it only says something along the lines of must be suitable for purpose. Does not specifically mention speed rating.
I'm not disagreeing with Steve on this, but Steve - won't most of the accelerative forces go through the rear tyres? I would have thought braking put more stress on the front tyres?
That aside, it does seem weird that they use the same technology/construction methods for the front and rear tyre, but one is V and the other Z. Presumably, if you could, you'd get the highest rating available to the tyre? So the inference is that the front tyre is genuinely not as robust as the rear.
Whilst typing Sunninghill have called back to say that the underwriters confirmed that there is no issue using V rated tyres on the car as regards invalidating insurance and have made a note on my policy details that I am using them.
I did point out that I am not actually using them - I have Z rated S02's on the car which have a lot of life left in them.
Insurance wise it really isn't as clear cut as people make out.
That said, I would still be in two minds about using them!!
Front wheels have lots of twisting forces as they are used to steer the car. Everytime you turn the wheel, part of the tyre wants to turn while the other doesn't. Rear wheels only suffer straight line acceleration mostly unless drifting and so on. I have worn out sidewall lettering and have pictures of me rolling tyres off rims during cornering so the forces are there. Big time. The front probably goes through more stress than the rears and one of the factors is the braking and acceleration. This is one of the reasons why extra air pressure is recommended for track days to try and reduce them. It also why a couple of laps on an underinflated tyre will kill it. ALl this twisting generates heat and too much will lead to failure. Higher speed rating tyres mean that they can cope with this heat better. So fit lower speed rating tyres and you have less capability to cope.
As for insurance. Ok they know about it. The car still doesn't meet the MOT spec. Could still leave you open to a problem. What happens if another car runs into you. They could use the tyre issue against you as a contributory factor. All this potential hassle to save a few pounds. Not worth it.
To me this is a stupid short cut. The tyres are maybe a few pounds cheaper but how much money do people spend on fuel and other running costs? It is a very small percentage. Owners seem to be willing to spend a lot of money on ally bits and ICE that do nothing for the safety and performance of the car yet quibble on spending a few pounds on a tyre that meets the manufacturer's spec.
Let's get this into perspective. Tyres are a safety factor. They should not be skimped on.
As for insurance. Ok they know about it. The car still doesn't meet the MOT spec. Could still leave you open to a problem. What happens if another car runs into you. They could use the tyre issue against you as a contributory factor. All this potential hassle to save a few pounds. Not worth it.
To me this is a stupid short cut. The tyres are maybe a few pounds cheaper but how much money do people spend on fuel and other running costs? It is a very small percentage. Owners seem to be willing to spend a lot of money on ally bits and ICE that do nothing for the safety and performance of the car yet quibble on spending a few pounds on a tyre that meets the manufacturer's spec.
Let's get this into perspective. Tyres are a safety factor. They should not be skimped on.
Steve
I agree with 99% of what you have said.
The only point you make that I don't now agree with is the insurance one - that the tyre shouldn't be used because it invalidates insurance. I don't think a one-liner 'You can't use them because it will invalidate your insurance' is factually correct. Your expanded explanation is much clearer.
The tyre may well be unsuitable for all the other reasons you suggest and I support you spreading the gospel on those issues.
Remember I replaced my brand new V rated Toyos and got new SO2's because I was concerned about them.
I'd have thought a pair of Avon rigid inflatables on the front would be more appropriate in this weather anyway!
I agree with 99% of what you have said.
The only point you make that I don't now agree with is the insurance one - that the tyre shouldn't be used because it invalidates insurance. I don't think a one-liner 'You can't use them because it will invalidate your insurance' is factually correct. Your expanded explanation is much clearer.
The tyre may well be unsuitable for all the other reasons you suggest and I support you spreading the gospel on those issues.
Remember I replaced my brand new V rated Toyos and got new SO2's because I was concerned about them.
I'd have thought a pair of Avon rigid inflatables on the front would be more appropriate in this weather anyway!
griff2be said: Steve
I agree with 99% of what you have said.
The only point you make that I don't now agree with is the insurance one - that the tyre shouldn't be used because it invalidates insurance. I don't think a one-liner 'You can't use them because it will invalidate your insurance' is factually correct. Your expanded explanation is much clearer.
The problem is that the only time this is tested is if you make a claim. If it is a big one then the insurance company will look at it in great detail.
You crash into a bustop as a result of taking avoiding action and injure 6 people. There was car where it should not have been and you had to swerve. As a result the car spun and you collided with the people.
If I was the other insurance company, I could quite rightly claim that as your car did not have tyres that complied with the manufacturer's OE specification and where of a lesser standard that this contributed to you losing control. Therefore you are liable (partially) as a result. You can say that you told the insurance company and they said that was OK. The other party could say well did you tell them that the tyres were inferior to the manufacturer's specification. Were they engineers and capable of deciding whether this posed a safety hazard. Did they talk to TVR to confirm that there was no issue? We talked to TVR who stated (to comply with their insurance) that only ZR rated tyres should be used...
All hypothetical but you can see how quickly you can get into a real potential problem, despite having told them you were using them. The V rated tyre leaves you wide open. Unfortunately it is not until you have a claim that the validity is actually tested.
The 520 is insured through Sunninghill and on the modified vehicle report (all 14 pages of it) I have to specify the original spec tyres and what I am using including the wheel sizes and speed ratings. They have a selection as I use different sizes for different activities.
Maybe the term invalidate is the wrong one but I hope this illustrates the potential issue.
Like I said at the beginning of this thread - SO3s boys. They stick, they roll, they are an advance in technology from Bridgestone, the maker of the much loved SO2s.
Tyres are the only thing between you and the road, get them right before anything else - brakes, suspension, engine. Next time you're v-maxing the Chimaera on the A26 to Calais (ahem) you'll be glad you chose the best.
(I'm not saying Toyos are bad BTW!).
T/.
Tyres are the only thing between you and the road, get them right before anything else - brakes, suspension, engine. Next time you're v-maxing the Chimaera on the A26 to Calais (ahem) you'll be glad you chose the best.
(I'm not saying Toyos are bad BTW!).
T/.
"TYRE SPEED SYMBOLS
For MOT requirements in this country, it is not necessary to fit a tyre with a speed rating to match the original vehicle fitment or the maximum speed of the vehicle. Tyres must be suitable for the purpose for which the vehicle will be used."
Which pretty much well covers a V rated tyre being more than suitable for the purpose given that the MOT test is a 'public'roadworthyness test. End of story.
Insurance: If the insurance company approves your tyre in writing they are indemnifying you under your insurance agreement. This point may be brought against your insurance company by another insurer but the onus would be on them to prove they were contributary to any accident. Now if you have an accident at 110mph on a motorway bend because the front washes out they may have something of a case, of course you probably wouldn't be around to know about it.
"You crash into a bustop as a result of taking avoiding action and injure 6 people. There was car where it should not have been and you had to swerve. As a result the car spun and you collided with the people." The speed rating of the tyre would have no effect in this situation unless of course you driving beyond the speed rating; which of course is unlikely. If your insurer has indemnified you with the knowledge of your running different speed rated front tyres then they have no legal backout for non-payment of a claim. If a CPS case was brought against you they would have to prove your tyre was not fit. Obviously a V rated front tyre will be perfectly capable of turning the car in, lets say, a 30mph avoidance manouvre. Also, then surely a (heavier, FWD) Mondeo running V rated fronts would be equally unfit for the task and subject to the same legal recourse in this case despite manufacturers recommendation. Basically it is a moot point. If your insurer agrees, and you have paperwork to this effect then you have no problem.
"The car still doesn't meet the MOT spec" see point one: "Tyres must be suitable for the purpose for which the vehicle will be used". Car will pass MOT.
"All this potential hassle to save a few pounds. Not worth it. To me this is a stupid short cut. The tyres are maybe a few pounds cheaper but how much money do people spend on fuel and other running costs?"
Well I chose my tyres on a balance of somewhat more than just cost, otherwise I'd be running around on retreads or Kumho budgets. The Toyo Proxes TX-1S has had an excellent write up in several articles from reputable sources. TVR themselves offer TOYO Proxes tyres as standard fit on the Tuscan. The fact that it is 15-20% cheaper than 'big-name' brands is a sweetner. My personal experience of running SO-2's then TX-1's showed a marked improvement in driving, particularly wet handling and aquaplaning. If its good enough for the factory....
>> Edited by trackdemon on Tuesday 15th October 18:36
For MOT requirements in this country, it is not necessary to fit a tyre with a speed rating to match the original vehicle fitment or the maximum speed of the vehicle. Tyres must be suitable for the purpose for which the vehicle will be used."
Which pretty much well covers a V rated tyre being more than suitable for the purpose given that the MOT test is a 'public'roadworthyness test. End of story.
Insurance: If the insurance company approves your tyre in writing they are indemnifying you under your insurance agreement. This point may be brought against your insurance company by another insurer but the onus would be on them to prove they were contributary to any accident. Now if you have an accident at 110mph on a motorway bend because the front washes out they may have something of a case, of course you probably wouldn't be around to know about it.
"You crash into a bustop as a result of taking avoiding action and injure 6 people. There was car where it should not have been and you had to swerve. As a result the car spun and you collided with the people." The speed rating of the tyre would have no effect in this situation unless of course you driving beyond the speed rating; which of course is unlikely. If your insurer has indemnified you with the knowledge of your running different speed rated front tyres then they have no legal backout for non-payment of a claim. If a CPS case was brought against you they would have to prove your tyre was not fit. Obviously a V rated front tyre will be perfectly capable of turning the car in, lets say, a 30mph avoidance manouvre. Also, then surely a (heavier, FWD) Mondeo running V rated fronts would be equally unfit for the task and subject to the same legal recourse in this case despite manufacturers recommendation. Basically it is a moot point. If your insurer agrees, and you have paperwork to this effect then you have no problem.
"The car still doesn't meet the MOT spec" see point one: "Tyres must be suitable for the purpose for which the vehicle will be used". Car will pass MOT.
"All this potential hassle to save a few pounds. Not worth it. To me this is a stupid short cut. The tyres are maybe a few pounds cheaper but how much money do people spend on fuel and other running costs?"
Well I chose my tyres on a balance of somewhat more than just cost, otherwise I'd be running around on retreads or Kumho budgets. The Toyo Proxes TX-1S has had an excellent write up in several articles from reputable sources. TVR themselves offer TOYO Proxes tyres as standard fit on the Tuscan. The fact that it is 15-20% cheaper than 'big-name' brands is a sweetner. My personal experience of running SO-2's then TX-1's showed a marked improvement in driving, particularly wet handling and aquaplaning. If its good enough for the factory....
>> Edited by trackdemon on Tuesday 15th October 18:36
trackdemon said:
Which pretty much well covers a V rated tyre being more than suitable for the purpose given that the MOT test is a 'public'roadworthyness test. End of story.
Surely, the tyre must always be capable of meeting the car's maximum power?
The car may not always spend it's life on the public highway, it might have a track day where the tyres deteriorated through heavy cornering, so much so that it contributed to an accident at a later date?
19560 said: Don't early Chimaeras come with 205/60R15 tyres? The problem here is that SO-2s and all of the other tyres at the top end of the market only come in a profiles up to 55% so that you cannot have OE and state of the art tyres. Its the same probelm for 350s and S series cars.
No it isn't as the factory have changed the tyre specs on these cars about 10 times so as long as the size is one of those there is no problem.
trackdemon said: "TYRE SPEED SYMBOLS
For MOT requirements in this country, it is not necessary to fit a tyre with a speed rating to match the original vehicle fitment or the maximum speed of the vehicle. Tyres must be suitable for the purpose for which the vehicle will be used."
OK.. So TVR fit ZR rated tyres as original equipment. The maximum quoted speed of a Chimaera or Griff is 165 mph. Sorry V rated tyres only goto 149 mph. They do not meet either of these criteria.
As for Toyos being good enough for TVR... They certainly don't fit them to the Griffs and Chimaeras.
Anyway. It is your car. Your risk and your potential problem.
raceboy said: RE71's are pre SO2's so straight to SO3's for you then,
They are actually pre-S01!
Not the best. Last set I had and it was some time ago, I sent to the great tyre dump in the sky at Mallory, power sliding round Gerrards. The technology has moved on shall we say.
The S02/S03 supply debate is strange. I bought a bulk load to feed the 520 (same size as the Griff rears) which came from Porsche. I think that many of the S02s that are still around are almost job lots that just appear. The S03 seems to be consistently available now. I have a set of so3s for the Griff front, ready and waiting. Probably put them on for the Winter to maintain max tread depth for wet weather driving and save the So2s for track days. I tend to circulate tyres as and when.
>> Edited by shpub on Wednesday 16th October 12:32
Very interesting thread! (Perhaps I am a bit sad.) 
I am confused about the mechanical strengths of different rated tyres though. The argument seems to be that the ZR rated tyres are better suited to performance cars due to the forces involved when accelerating, braking and cornering. Whilst this may be the case, why are the forces on a TVR any greater than any other car? Lets face it, TVR's are quick, but they (or most other cars for that matter) cannot accelerate faster than they can brake, so braking must exert a greater force on the tyres. Equally, TVR's are do not weigh very much. Surely a Land Rover discovery diesel can exert much greater forces on tyres when cornering as they must be double the weight.
Whilst I am not advocating changing my S02's for a cheaper alternative, the science behind the arguments seems to be flawed. Basically I don't understand why the Land Rover HR (I guess) rated tyres perform fine when the stresses seem to be greater.
Jamie.
I am confused about the mechanical strengths of different rated tyres though. The argument seems to be that the ZR rated tyres are better suited to performance cars due to the forces involved when accelerating, braking and cornering. Whilst this may be the case, why are the forces on a TVR any greater than any other car? Lets face it, TVR's are quick, but they (or most other cars for that matter) cannot accelerate faster than they can brake, so braking must exert a greater force on the tyres. Equally, TVR's are do not weigh very much. Surely a Land Rover discovery diesel can exert much greater forces on tyres when cornering as they must be double the weight.
Whilst I am not advocating changing my S02's for a cheaper alternative, the science behind the arguments seems to be flawed. Basically I don't understand why the Land Rover HR (I guess) rated tyres perform fine when the stresses seem to be greater.
Jamie.
[quoteWhilst I am not advocating changing my S02's for a cheaper alternative, the science behind the arguments seems to be flawed. Basically I don't understand why the Land Rover HR (I guess) rated tyres perform fine when the stresses seem to be greater.
The science is not flowed just very very complicated. In a nutshell it is all about controlling the tyre wall and tread to stop distortion and reduction of the tyre contact patch while the tyre is operating. It includes managing the heat generated so that the tread doesn't overheat and die. It is all about preventing the tyre from moving and so on. It is all about understanding how the tread moves and resists the movement. Bear in mind the most stress on tread is when it moves (that's why F1 driver weave to get heat in their tyres) and it is also when the most grip is needed. A 2 ton rangie does not corner at anywhere near the speeds that a TVR can/does and its tyres don't experience that level of stress. Under braking they do but try braking in anything but a straight line and it is Goodnight Vienna.
Drive a TVR round a roundabout quickly and the car is pulling close to 1 G (surprised me but that was what the Ap22 G meter reported 0.84G) but the speed is not high (40ish) mph. You know have 1 ton of car accelerating sideways at almost 1 G which is only being kept in place by four foot size patches of rubber. That is one hell of a lot of stress on the sidewall and tread block. Now imagine what happens as the sidewall distorts, rolls under the rim and reduces the contact patch. Need I say more.
A Rangie wouldn't even get close to those stresses!
Steve
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