Discussion
domster said:
Tony T runs lovely 18s on his 964 C2 RSalike.
Not sure what the 996 offset etc. is like, in terms of looks, clearance or handling. The diameter is only one dimension
Thanks Dom.
citychap26 said:
Hi
I have just got some 18's of a 996. I have also just got some 15mm spacers for the rears. Any on running 18's ?
Will I need to lower the car?
Cheers
Sunil
PS anyone got pics?
I'm running 18ins Gt1 Veloces, which are 47 offset with 265/35 rears; car has H+R supercup coilovers and is lowered to RS specs. I used a 25mm spacer and had the rear arches streched to prevent fouling.
I also run 17inch 996 wheels, can't remember the offset but 62 rings a bell, which is why I fitted spacers in the first place - my original spacers were 18mm items, so your 15mm ought to work (47 offset is considered the ideal for lowered track 964 narrow bodied cars).
Lowering the car is likely to make problems worse rather than better. Running my car lowered with 17ins RUF alloys with 47 offset and 255/35 tyres and 3deg negative camber I had about 2mm clearance from the fender lip and in enthusiastic driving the tyre would hit the swinging arm, oil line and the inner wheel well but still hit the fender lip occasionaly.
>> Edited by tony.t on Wednesday 30th March 18:05
pesty said:
Tonyt.
Love those alloys on your motor. are they lighter than 18inch Porsche jobbies?
They are advertised at 30.6kg for 4 but I weighed them and they are nearer 8kg each.
About 2kg per wheel lighter than 17ins Cup2s.
IIRC 18ns hollow spokes are 27lb each.
edited to add;
Rear wheel 10J x 18ins 18lb13oz 8.52kg
Front wheel 8.5J x 18ins 18lb3oz 8.24kg
>> Edited by tony.t on Wednesday 30th March 20:28
From Adrian Streathers book:
Porsche Tech Bulletin
April 15, 1993
Retrofitting 18" wheels on Porsche vehicles which do not have 18" wheels as original equipment are NOT ALLOWED.
Apparently endurance tests in US revealed loosened bolts and threaded connections on front wheel carriers plus subsequent fracture of components. Fractures may also occur in front strut mounts and in the body in the area of the rear suspension...such damage can occur without warning...
Take care out there!!
Mel
Porsche Tech Bulletin
April 15, 1993
Retrofitting 18" wheels on Porsche vehicles which do not have 18" wheels as original equipment are NOT ALLOWED.
Apparently endurance tests in US revealed loosened bolts and threaded connections on front wheel carriers plus subsequent fracture of components. Fractures may also occur in front strut mounts and in the body in the area of the rear suspension...such damage can occur without warning...
Take care out there!!
Mel
Thanks for the offer but I do like the look of my 18inch wheels and intend to keep them.
Its just that now I am getting used to the car and gradualy driving it harder I cant help but feel the wheels look better than they drive. Hence teh would like to try just to see what the difference would be.
If some cheap 17inch cups appear on E-bay I may go for them.
I have also just put 4 brand new tyres on at£580
and they are replicas not genuine Porsche wheels I think as they do not have the offset and width marked by the valve.
Its just that now I am getting used to the car and gradualy driving it harder I cant help but feel the wheels look better than they drive. Hence teh would like to try just to see what the difference would be.
If some cheap 17inch cups appear on E-bay I may go for them.
I have also just put 4 brand new tyres on at£580
and they are replicas not genuine Porsche wheels I think as they do not have the offset and width marked by the valve.The standard wheel on the 993 was initally 16 inch with 205-55 front and 245-45 rear. On this combination it is a joy to dive on the road. Grip is still exceptional but you can explore the limits in relative safety, things happen more slowly and the ride is smooth. I'm keeping my old fashioned 16's.
pesty said:
Thanks for the offer but I do like the look of my 18inch wheels and intend to keep them.
Its just that now I am getting used to the car and gradualy driving it harder I cant help but feel the wheels look better than they drive. Hence teh would like to try just to see what the difference would be.
If some cheap 17inch cups appear on E-bay I may go for them.
I have also just put 4 brand new tyres on at£580
It cost me £500 for a set of 205/55s for my 205 1.9 GTI in 1989. Tyre prices are MUCH better value now
Really wouldn't advise 18"s on a 964 have tried it and it tramlined like a blob. The ride is way better with 17"s to be honest same as my old 993, The car came with them an I changed it back to 17"s and tranformed the car - miles better round bends and better on long distance too. Also - no explanation for it, but its seemed more economical too on the computer mpg - maybe I was imagining it!
Sorrry to pee on your bonfire for larger wheels - also not convinced that you have the right offset for the 996 wheels anyhow.
Bod
Sorrry to pee on your bonfire for larger wheels - also not convinced that you have the right offset for the 996 wheels anyhow.
Bod
Melv said:
From Adrian Streathers book:
Porsche Tech Bulletin
April 15, 1993
Retrofitting 18" wheels on Porsche vehicles which do not have 18" wheels as original equipment are NOT ALLOWED.
Apparently endurance tests in US revealed loosened bolts and threaded connections on front wheel carriers plus subsequent fracture of components. Fractures may also occur in front strut mounts and in the body in the area of the rear suspension...such damage can occur without warning...
Take care out there!!
Mel
I believe Adrian Streather has changed his tune somewhat over 18ins wheels since his collaberation with Sportec.
Sportec and Cargraphic,RUF and Techart all have TUV approved 18ins wheels for NB 964s.
Personaly I would be interested to hear of anyone who has had, or has known anyone or has heard of a friend of friend who has suffered a component failure due to the fitment of 18ins wheels to a NB 964.
The strengthened 964RS came with 17ins wheels as did the ( AFAIK) 965. The 964 3.8RSR and "Cup" cars came with 18ins wheels. The Cup cars ran slicks, however it appears the suspension of Cup cars is unable to withstand the strain of 18ins wheels and slicks leading to failure of the rubber bushes. Of course this is not relevant to race cars were components are checked after ever race, and replaced if required, and as such is not directly comparable to endurance testing of road cars.
I can understand how heavier wheels can induce extra strain on the car but I am at a loss as to how a lighter wheel/tyre combination will cause problems. I am willing to believe that the centrifugal/centripetal forces will increase with the increase in distance from the axel of the wheel rim, where we would expect, like for like, the greater amount of weight of the wheel to be. However in spun aluminium or magnesium alloy the rim will be lighter.
All of which ignores the tyre s contribuition to weight which can vary by as much as 10lbs by make.
If anyone has any empirical proof otherwise I would be interested to see it.
>> Edited by tony.t on Saturday 2nd April 02:23
AJAX50 said:
I thought the main reason for larger diameter wheels is to increase the brake disc size. If the brakes are OK then the next priorities should be width and unsprung weight which are best optimised with smaller diameter wheels, is this correct?
In general running larger diameter wheels allows lower profile tyres since it's generally desirable to retain the same tyre and wheel diameter. Lower profile tyres have stiffer side walls on a like for like basis allowing lower tyre pressures and hence a greater tyre contact point.
Melv said:
Not just 18"'s Tony. Running slicks on 17" I've just fitted poly bushed front wishbones after the OE items failed at 10,000kms.....not bad for two and a half years of track days though!
If you don't mind where, who and how much for the poly wish bones?
Did you consider monoballs?
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