...Now Sydl like I said I agree with you 100% and you are correct, but my recommendation is based on my knowledge of Hartge's TUV criteria. And it is on that basis that I have recommended this package.
I have no doubt that Hartge's engineering is up to scratch but there are countries that do not accept TUV or other standards except their own.
The issue of load rating is one that is incredibly specific. For example, there are some closed-road tarmac rallies in Australia run under FIA rules. The scrutineering requirement is that the cars be roadworthy. This is interpreted to mean that the cars run tyres rated by the manufacturer in their homologation papers. Essentially this means that the cars need to find R-compound (eg sticky competition rubber) that is road legal (ie no slicks) that meets the speed and the load rating of the manufacturer's car. So a Porsche GT3 or a Ferrari 360 for example, needs to find tyres at the OEM tyre's rating. It is easy for scrutineers to check this compliance because the tyre placard is stuck on the driver's door and the rating stated can be compared with what is stamped on the side of the tyre. If the two don't match, then the competitor has to get new tyres or the car can't compete.
This procedure is essentially the same when an insurance assessor investigates a damaged car. One of the first things they look for are non-standard aftermarket parts. Tyres, wheels, exhaust, engine modifications etc. And if they find anything that is non-standard they look at it with a microscope. If it doesn't comply then they would deny coverage. If you were the car's owner you would then turn to the company that sold you the parts (wheels etc.) that made your car unroadworthy and you would probably have a highly arguable case. Certainly in Australia you would find it very hard to buy a wheel and tyre package that was below the manufacturer's load rating from a shop because they have been told by their insurance company that the owner's of the shop would be personally liable for their customer's loss.
Wheels and tyres in particular, there have been many reported cases where if the tyres are greater or less than the original width and rolling radius by a certain %, the car is deemed to be unroadworthy. So if you go +1, then you have to match the new tyre's aspect ratio properly. Similarly, the new tyres must be the same load rating.
Of course, your country's insurance company and laws may be different, but given the international nature of insurers I would bet that they use similar procedures regardless of country.
If I were living in Europe and wanted to use the 21" wheels and tyres it would be very simple - just ring your insurer and DMV. And if you do, please post their response in this thread so we can be better informed of the situation in your country. What I have stated is the situation to the best of my knowledge in Australia.
If I were living in Europe and wanted to use the 21" wheels and tyres it would be very simple - just ring your insurer and DMV. And if you do, please post their response in this thread so we can be better informed of the situation in your country. What I have stated is the situation to the best of my knowledge in Australia.
Hi Sydl
Like I said I agree with you 100%. Yes you should inform your insurance company right from the offset. I understand the point you make regarding the racing to FIA rules, and its for those reasons dor instance the M3 CSL comes with the tyres it does.
As to the situation in Australia, I am all to aware of it. My dealer there was Bob Jane's T-Marts and the problems I used to get where I would have to change offsets for a particular fitment, even though everywhere else in the world it was never as a problem, used to cause me nightmares. We spoke about this when I was there last year.
Sydl if you think Australia is bad dont even go there with Switzerland!!!!!
I think this is a subjective thing but you are 100% correct, I would always recommend that you check with your innsurance company before changing ANY part on your car not just wheels and tyres.
I believe there is a member there already with the 21" wheels and tyres.
I would not have any issues with my insurance company, they would probably use it to rip me off for some more money the bas$%rds buy thats about it in the UK.
...Sydl if you think Australia is bad dont even go there with Switzerland!!!!!
Really? Strict there too? Does that mean that a TUV approved wheel/tyre combo like Hartge would not be legal in Switzerland?
I think the reason why it's got so bad in the last few years is due to a lot of the performance turbo cars (WRX, Evos) having aftermarket turbos, wheels, tyres, exhausts, pop-off valves and god knows what else added to the cars. These cars then have accidents and the insurers look for an escape clause.
Really? Strict there too? Does that mean that a TUV approved wheel/tyre combo like Hartge would not be legal in Switzerland?
I think the reason why it's got so bad in the last few years is due to a lot of the performance turbo cars (WRX, Evos) having aftermarket turbos, wheels, tyres, exhausts, pop-off valves and god knows what else added to the cars. These cars then have accidents and the insurers look for an escape clause.
In Switzerland they have no problem with TUV, but a lot of manufacturers including my old company would change offsets to improve looks and handling. In Switzerland there is minimal deviation from the original offset and width of the wheels.
We used to make a 9 x20" wheel for the Bentley GT with a 16mm ofset for the rear and 31mm off sett for the front. The original was 9 x19 with an offset of 41mm. The fronts were JUST legal but the backs we could not use. So for there I used to have to ship ET31 wheels. Used to screw my stock up something stupid!!!!
The Hartge tyres are made for the load for the M5. Anything else would be totally lunacu from Hartge to sell to the public. I will reply with a detailed post below.
Quote:
Originally Posted by sydl
I think this is a very dangerous and reckless recommendation. The only thing that is improtant IMO is whether his insurance company will compensate him for damage that occurs when he is on a tyre that does not conform to the manufacturers' specifications.
The tyre load rating spec for the M5 is clearly stated as 710 and 775kg - so if you are on a tyre that is load rated at less than that in some countries the car is deemed to be unroadworthy. The consequence of that is that insurance policies are void. Obviously it's still safe to drive but that is not the point from the point of who will be responsible for damage that occurs to the car or by the car.
If you are OK with driving your M5 without insurance, then you can put whatever rubber you want - but if you want to know that you're insured - just make one call and ask your insurer "if I have an accident in this car with these +2 wheels and tyres is my policy valid and hey say yes and give it to you in writing" then go for it.
I talked to Hartge today, Volker one of the responsible technicians. I'll try to explain below. I should read more into definition of load index but a summary is below.
Load index is decided by formerly ETRTO (European Tyre and Rim Technical Orginazation), it is now under well known ISO (International Organazation for Standardization). Load index is just another way of saying load in kilograms [kg] per wheel. For example:
Load index Load [kg]
96 710 kg
95 690 kg
94 670 kg
The ISO decides the width and load index for every tyre size. A tyre manufacturer can specify "Usual" or "Extra load" for the particluar tyre he choose. Extra load you add 4 to this index.
BMW M chosed "Regular" because of the 19' dimension and their choise of combination of comfort and sport. More exactly 96 for fron wheels and 99 for rear wheels. So if it existed, a front wheel to the M5 in "Extra load" would have load index 100. However as seen above there is no need for that since the wheels could carry the M5 without problems.
Important fact is: you cannot change load index more than "Extra load" (+4).
Load index is a result function of various variables with the most important ones are air volume and tyre structure. Air volume on a 21' is less than on a 19' since the inner radius is larger of the tyre with almost remained outer radius of the tyre as we calcuted here.
Consequently a larger wheel must have a lower load index since it has less volume of air.
Hartge have worked with Continental to develop these tyres and this dimension is available from Continental (Hartge partner), Michelin and Pirelli. Hartge wheels are "Extra load" and in this dimension it is the only tyre available (they are not available in "Regular").
Maximun load M5 front wheels: 545 kg. Hartge have 650 kg
Maximum load M5 rear wheels: 635 kg. Hartge have 710 kg
Also, as a "advanced course" Hartge can prove that their tyre is OK for 320 km/h and BMW M5 standard are approved for 310 km/h. This was hard to understand over the phone but I assume their calculations are correct, and that goes in line with BMW M own limiter at 305 km/h.
Definition: Load on tyre: axle load / 2.
Further facts:
The Hartge wheel weight a bit more due it's increased size (of course) and also the design of the spokes. The spokes could have been hollow but this would have lead to a much higher price.
I talked to Hartge today, Volker one of the responsible technicians. I'll try to explain below.
Gustav, this is very interesting, thanks for taking the trouble to talk to Hartge but the obvious question is:
Q. Why aren't the 21" tyres just designated with a load rating of 96 for the front and 99 for the rear if that is what they are? For the front for example, why is it necessary for Continental to say it is "92 XL" (which Hartge and not Continental told you is equivalent to 96)? Either it is 96 or it isn't. The Continental web site just says: "XL - Extra Load (designates specially reinforced tyres)" - it doesn't say that it is +4. http://www.conti-online.com/generato...r_tyre_en.html
The point is whether you want to have the argument with the authorities and insurance company. The will just look at the load rating, and *not* the load rating + the "XL" because they are just not interested in what the "XL" means.
Is it possible for you/someone to call your insurance company and ask them whether they are happy to insure an M5 with 92 XL when BMW wants 96 and see what they say on this topic?
Anyone want to ring Continental in Germany?
Last edited by sydl; 30th September 2005 at 14:40.
Thing is, it is ISO that decides load rating for the tyre, not Continental. That is what that organasation purpose is as far as tyre ratings if I understood it correctly.
Quote:
Originally Posted by sydl
Gustav, this is very interesting, thanks for taking the trouble to talk to Hartge but the obvious question is:
Q. Why aren't the 21" tyres just designated with a load rating of 96 for the front and 99 for the rear if that is what they are? For the front for example, why is it necessary for Continental to say it is "92 XL" (which Hartge and not Continental told you is equivalent to 96)? Either it is 96 or it isn't. The Continental web site just says: "XL - Extra Load (designates specially reinforced tyres)" - it doesn't say that it is +4. http://www.conti-online.com/generato...r_tyre_en.html
The point is whether you want to have the argument with the authorities and insurance company. The will just look at the load rating, and *not* the load rating + the "XL" because they are just not interested in what the "XL" means.
Is it possible for you/someone to call your insurance company and ask them whether they are happy to insure an M5 with 92 XL when BMW wants 96 and see what they say on this topic?
my insurance company (BMW Original Insurance Sweden) had a simple enough answer over the phone.
If the tire/wheel combination passes the "Besiktning" or MOT equivelant in the UK - it is allowed to be a valid upgrade with the insurers at no extra costs.
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