997 RS MKI 8/32 R&P and 18" wheels. Anyone ?
10-11-2010, 04:54 AM
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997 RS MKI 8/32 R&P and 18" wheels. Anyone ?
I'm looking for a secondary wheel set for my 997 MKI RS.
As 19" tires are not cheap and there are few options in this size, I'm considering to go to 18", but my car has 8/32 R&P so maybe this combination will be excessive, even for a track only car.
Anyone here is using 18" whit 8/32 ? I would be grateful for your comments about.
Regards.
As 19" tires are not cheap and there are few options in this size, I'm considering to go to 18", but my car has 8/32 R&P so maybe this combination will be excessive, even for a track only car.
Anyone here is using 18" whit 8/32 ? I would be grateful for your comments about.
Regards.
10-11-2010, 12:26 PM
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the 997.1 RS
has
235/35/19 front and wheels are 8.5x19 et53
305/30/19 rear and wheels are 12x19 et51 *plus 5mm spacers
rear diameter for the oem wheel and tyre is 66.56cm
if you go in 18" you can easily keep the same diameter by increasing the profile of the tyre
for example a 305/35/18 would be 67,07cm and a 335/30/18 would be 65.82cm etc etc
So it can be done with many different sizes and combinations and still maintain almost same overall diameter and revs per kilometer as the oem wheels and tyres.
Take care to use the appropriate tyres in the front as well so the rear to front ratio of overall diameters is not far off the oem one so to avoid ABS problems. Up to 4% difference is ok.
Do a search here to see what others are using in 18" for the 997 GT3s.
Btw I have the cup R&P on a 6gt3 and I use 315/30/18 *over. Diameter 64.62 and since the gear ratios are quite close between the 6 and 7 I can tell you that I think that the first gear is too short for anything but a drag race. I do like it but It would be better to change gears in addition to the shorter ring and pinion this way you can space them as you like and also fix the gear ratios gaps 2/3/4.
John
the 997.1 RS
has
235/35/19 front and wheels are 8.5x19 et53
305/30/19 rear and wheels are 12x19 et51 *plus 5mm spacers
rear diameter for the oem wheel and tyre is 66.56cm
if you go in 18" you can easily keep the same diameter by increasing the profile of the tyre
for example a 305/35/18 would be 67,07cm and a 335/30/18 would be 65.82cm etc etc
So it can be done with many different sizes and combinations and still maintain almost same overall diameter and revs per kilometer as the oem wheels and tyres.
Take care to use the appropriate tyres in the front as well so the rear to front ratio of overall diameters is not far off the oem one so to avoid ABS problems. Up to 4% difference is ok.
Do a search here to see what others are using in 18" for the 997 GT3s.
Btw I have the cup R&P on a 6gt3 and I use 315/30/18 *over. Diameter 64.62 and since the gear ratios are quite close between the 6 and 7 I can tell you that I think that the first gear is too short for anything but a drag race. I do like it but It would be better to change gears in addition to the shorter ring and pinion this way you can space them as you like and also fix the gear ratios gaps 2/3/4.
John
