Are 18in wheels safe
02-11-2006, 06:21 AM
#61
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As Adrian and others have said, if you put 18" wheels on a car with tyres of the same diameter as 16" or 17" wheels, obviously the tyres will have a reduced sidewall. The side wall of the tyre absorbs a lot of the shocks from the road. If you reduce the sidewall, then you are going to be transmitting more of the shocks to other parts of the car, such as the suspension and bodywork. As Adrian pointed out Audi had big problems with the RS4 in Europe with this issue, which they allegedly tried to solve my making the rims less stiff, which might be why so many owners complained about wheels deforming in potholes!
There are several 964 owners in Australia who are racing on 18" wheels, but I'd be interested to know how many of them were aware of the notice from Porsche regarding the use of 18" wheels on the 964. I'll ask them next time I see them.
DavidP
There are several 964 owners in Australia who are racing on 18" wheels, but I'd be interested to know how many of them were aware of the notice from Porsche regarding the use of 18" wheels on the 964. I'll ask them next time I see them.
DavidP
02-11-2006, 10:22 AM
#62
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Originally Posted by adsc4s
As far as your Fikse and CCW wheels Gary, no one really cares what you do or do not do. Adrian is simply the messenger.
02-11-2006, 10:52 AM
#63
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Originally Posted by Gary R.
I fully understand that he was just putting out information, also understand that he is running "approved" 19" wheels on his 964.
02-12-2006, 05:23 AM
#65
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You are overestimating TUeV. They will check if larger, wider wheels rub somwhere, if the brakes have clearance, etc. They will not make long-term observations, just consider road usability. Same with springs. They will look at clearance, check if the car remains driveable, etc. They don't care if the structure falls apart after five years, because they would find out during the German two-year inspections and would shut down your car then.
However, TUeV also works as an independent expert organisation and will give you a expert statement if you order them examine/witness certain aspects (f.e. "what damage cause 18 inch wheels driven on a C2 coupe for 100.000 km?"). (Adrian is suggesting this for Sportec, but we would have to ask this company) Nevertheless, most manufacturers would have it the way in the upper paragraph. When you buy parts you are issued a simple TUeV statement for road usability which will enable you to use the parts on a car registered in Germany. So there has to be only one test instead of hundreds of tests on each individual, modified car.
So the reason why everybody looks at TUeV is because it is a mandatory prerequisite for modifying your car without loosing insurance. Nothing else.
Ruf rips the whole car apart and reassembles a new, different car. I wouldn't take this as a reference.
I take Porsche's bulletins serious and would really love to find out more about the mentioned ban list and which cars got taken off it. All the bulletins I know about 964/993 are very clear and not older than three years.
Best regards,
Felix
However, TUeV also works as an independent expert organisation and will give you a expert statement if you order them examine/witness certain aspects (f.e. "what damage cause 18 inch wheels driven on a C2 coupe for 100.000 km?"). (Adrian is suggesting this for Sportec, but we would have to ask this company) Nevertheless, most manufacturers would have it the way in the upper paragraph. When you buy parts you are issued a simple TUeV statement for road usability which will enable you to use the parts on a car registered in Germany. So there has to be only one test instead of hundreds of tests on each individual, modified car.
So the reason why everybody looks at TUeV is because it is a mandatory prerequisite for modifying your car without loosing insurance. Nothing else.
Ruf rips the whole car apart and reassembles a new, different car. I wouldn't take this as a reference.
I take Porsche's bulletins serious and would really love to find out more about the mentioned ban list and which cars got taken off it. All the bulletins I know about 964/993 are very clear and not older than three years.
Best regards,
Felix
02-12-2006, 10:57 AM
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ruf do do that . they also sell accesories seperately ........
ruf also sell 18" wheels for a 964 .
porsche also "reassembled a new , differrent car" ........... the rs
i phoned my local porsche opc to get a price for my whhels . too expensive , so i bought my 18" porsche 964 speedlines from a porsche specialist , had the re-furbed at another porsche specialist , had the tyres fitted at another porsche specialist , then yet another porsche specialist took them off and re-fitted them when the sorted my red calipers .
no-one said anything . even if they had talked about this buliten , i probobly would have said " so what . you read about it , i'll drive it "
ruf also sell 18" wheels for a 964 .
porsche also "reassembled a new , differrent car" ........... the rs
i phoned my local porsche opc to get a price for my whhels . too expensive , so i bought my 18" porsche 964 speedlines from a porsche specialist , had the re-furbed at another porsche specialist , had the tyres fitted at another porsche specialist , then yet another porsche specialist took them off and re-fitted them when the sorted my red calipers .
no-one said anything . even if they had talked about this buliten , i probobly would have said " so what . you read about it , i'll drive it "
02-13-2006, 05:08 AM
#68
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What better testimonial to the "RUF 18" WHEELS", then that of two other Porschists, actively involved in this wheel size question and answer...
But... I’m still very confused however, and still not sure what to do... Do I get, 16" wheels, 17" wheels, 18" wheels or 19" wheels?!?!...
Does anyone have any information on the "MiniLite 15" Magnesium Wheels"... And hey, look how much extra tire rubber you get at that size, now that’s good value... Fine, there’s another option to this intriguing dilemma... "What about the 15" wheel"...
Confused and lost, but searching for the truth at rennlist.com,
Marc...
PS. Who said owning a Porsche wasn’t fun...
But... I’m still very confused however, and still not sure what to do... Do I get, 16" wheels, 17" wheels, 18" wheels or 19" wheels?!?!...
Does anyone have any information on the "MiniLite 15" Magnesium Wheels"... And hey, look how much extra tire rubber you get at that size, now that’s good value... Fine, there’s another option to this intriguing dilemma... "What about the 15" wheel"...
Confused and lost, but searching for the truth at rennlist.com,
Marc...
PS. Who said owning a Porsche wasn’t fun...
02-13-2006, 09:49 AM
#69
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Marc, I think you may have missed the point. It is the tire WIDTH that puts the extra stress on the front suspension, not the rolling diameter. If you want to be safe(r) then I would say buy whatever size wheels you want as long as:
A. The rolling diameter with tire is equal to OEM available tire/wheel sets.
B. The tire width is equal to OEM available tires.
C. The combined tire/wheel weight is equal to or less than OEM available tire/wheel sets.
OR do like me, put on what you like (and of course is LEGAL in your country) and keep a close eye on your front suspension components.
A. The rolling diameter with tire is equal to OEM available tire/wheel sets.
B. The tire width is equal to OEM available tires.
C. The combined tire/wheel weight is equal to or less than OEM available tire/wheel sets.
OR do like me, put on what you like (and of course is LEGAL in your country) and keep a close eye on your front suspension components.
02-13-2006, 04:15 PM
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marc ,
i think brake size might be an issue with 15's !!!
though i'm sure a certain make/model of 15's will fit over them .
with low profile tyres , 15's will liven up your acceleration too !!!
tyre width is only the problem during high , high , high speed repetitive cornering !!!!!
any extra grip/g-forces/shock that my carrera-cup 18's put on my car will be immaterial at 70 mph max on a strait motorway
i think brake size might be an issue with 15's !!!
though i'm sure a certain make/model of 15's will fit over them .
with low profile tyres , 15's will liven up your acceleration too !!!
tyre width is only the problem during high , high , high speed repetitive cornering !!!!!
any extra grip/g-forces/shock that my carrera-cup 18's put on my car will be immaterial at 70 mph max on a strait motorway
02-14-2006, 06:59 AM
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Porsche is taking this matter seriously as those customers claiming "I drive it" could come back and make product liability claims. It's all about responsibility and Porsche has a image to loose.
I believe Porsche's reasoning comes from racing experiences. On a race track you have curbs and the stress on the car hitting a curb is immense. The tire plays a big role in dampening this impact and the dampening capability is vastly impaired by 18 or 19 inch wheels. So, I don't think it is about tire width, but the dampening capability. In fact a wider tire on the same rim might even have better dampening capability.
If you are doing nothing else than cruising at 70 mph on the highway I wouldn't give a damn about wheel size.
If you are racing I probably wouldn't give a damn either because the stress on the car is so high, that the wheels play one role inter pares, only.
Felix
I believe Porsche's reasoning comes from racing experiences. On a race track you have curbs and the stress on the car hitting a curb is immense. The tire plays a big role in dampening this impact and the dampening capability is vastly impaired by 18 or 19 inch wheels. So, I don't think it is about tire width, but the dampening capability. In fact a wider tire on the same rim might even have better dampening capability.
If you are doing nothing else than cruising at 70 mph on the highway I wouldn't give a damn about wheel size.
If you are racing I probably wouldn't give a damn either because the stress on the car is so high, that the wheels play one role inter pares, only.
Felix
