The 997 undersides, wheels
09-25-2006, 08:13 PM
#1
Poseur
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The 997 undersides, wheels
This weekend I did what every 997 owner should eventually do,--put the car up on stands, pull the wheels, and check out what Porsche did to these cars.
I know Dave has done a fair amount of wheel swaping on his 9974S but wondered if others have personally pulled the rims off their cars. I was simply shocked at the size of these wheels and tires. My front (8.5 x 19 XRRs) are like my rears USED to be, but today's rears are enormous! With 11.5 by 19s back there we're talking about a wheel that weighs about 100 lbs mounted and balanced. That's for each corner. No wonder that Porsche was looking for some weight trimming with the PCCBs and other component material changes.
Will post some pictures here shortly of what I discovered inside this technological marvel.
I know Dave has done a fair amount of wheel swaping on his 9974S but wondered if others have personally pulled the rims off their cars. I was simply shocked at the size of these wheels and tires. My front (8.5 x 19 XRRs) are like my rears USED to be, but today's rears are enormous! With 11.5 by 19s back there we're talking about a wheel that weighs about 100 lbs mounted and balanced. That's for each corner. No wonder that Porsche was looking for some weight trimming with the PCCBs and other component material changes.
Will post some pictures here shortly of what I discovered inside this technological marvel.
09-26-2006, 12:35 AM
#2
There is absolutely no way a rear wheel/tire weighs 100 pounds. No way, not even close. Measure it with a scale and get back to us.
EDIT: Unless you mean for the pair, which in that case yes thats very possible.
EDIT: Unless you mean for the pair, which in that case yes thats very possible.
09-26-2006, 09:45 AM
#5
Chandler!
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Originally Posted by Edgy01
This weekend I did what every 997 owner should eventually do,--put the car up on stands, pull the wheels, and check out what Porsche did to these cars.
I know Dave has done a fair amount of wheel swaping on his 9974S but wondered if others have personally pulled the rims off their cars. I was simply shocked at the size of these wheels and tires. My front (8.5 x 19 XRRs) are like my rears USED to be, but today's rears are enormous! With 11.5 by 19s back there we're talking about a wheel that weighs about 100 lbs mounted and balanced. That's for each corner. No wonder that Porsche was looking for some weight trimming with the PCCBs and other component material changes.
Will post some pictures here shortly of what I discovered inside this technological marvel.
I know Dave has done a fair amount of wheel swaping on his 9974S but wondered if others have personally pulled the rims off their cars. I was simply shocked at the size of these wheels and tires. My front (8.5 x 19 XRRs) are like my rears USED to be, but today's rears are enormous! With 11.5 by 19s back there we're talking about a wheel that weighs about 100 lbs mounted and balanced. That's for each corner. No wonder that Porsche was looking for some weight trimming with the PCCBs and other component material changes.
Will post some pictures here shortly of what I discovered inside this technological marvel.
09-26-2006, 11:04 AM
#7
Burning Brakes
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The 305/30YR-19 Pilot Sport 2 (XL, N1) weighs 29 lbs unmounted, Dan... you can't mean that the wheels weigh 70 lbs !?! I know that they are enormous, but... dude!!!
-don
-don
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09-26-2006, 02:10 PM
#8
Porsche Factory Carrera S
8x19" 22 lbs. 4 oz.
11x19" 27 lbs. 12 oz.
Porsche Factory Carrera Classic
8x19" 23 lbs. 10 oz.
11x19" 28 lbs. 11 oz.
Porsche Factory Carrera Sport Design
8x19" 24 lbs. 3 oz.
11x19" 28 lbs. 3 oz.
Porsche Factory Carrera Sport
8.5x19" 24 lbs. 2 oz.
11.5x19" 29 lbs. 4 oz.
A 295/30/19 Michelin PS2 weighs 29lbs. The 305/30/19 Bridgestone weighs 34lbs
http://www.tirerack.com/tires/Spec.j...irePageLocQty=
I'm a nutcase about weight, especially wheels, tires and brakes. There's a lot of performance being sucked up accelerating and decellerating those monsters, not to mention (I guess I am) the gyroscopic effect on turn-in and direction changes and the stiffer dampening required to slow the movement of heavy wheels/tires/brakes. It's amazing the difference in feel if you take weight off in this area.
The stock 19" lobster claws weigh 100lbs for a set of 4. I've dropped about 36lbs of weight with the PCCB's and will drop another 38lbs with new wheels, tires and lugs when they arrive. The net total reduction of approximately 74lbs should be the rough equivalent of removing 500lbs of static weight from the car. I'll report more when they arrive and I have some miles on them.
Dan - I agree with you. I had my 295 rear tire off due to a flat a week ago and the size of these wheel/tires is simply astonishing. The new ones will be 315/30/18 so they will look even more massive and provide astonishing grip, I'm sure.
MC
8x19" 22 lbs. 4 oz.
11x19" 27 lbs. 12 oz.
Porsche Factory Carrera Classic
8x19" 23 lbs. 10 oz.
11x19" 28 lbs. 11 oz.
Porsche Factory Carrera Sport Design
8x19" 24 lbs. 3 oz.
11x19" 28 lbs. 3 oz.
Porsche Factory Carrera Sport
8.5x19" 24 lbs. 2 oz.
11.5x19" 29 lbs. 4 oz.
A 295/30/19 Michelin PS2 weighs 29lbs. The 305/30/19 Bridgestone weighs 34lbs
http://www.tirerack.com/tires/Spec.j...irePageLocQty=
I'm a nutcase about weight, especially wheels, tires and brakes. There's a lot of performance being sucked up accelerating and decellerating those monsters, not to mention (I guess I am) the gyroscopic effect on turn-in and direction changes and the stiffer dampening required to slow the movement of heavy wheels/tires/brakes. It's amazing the difference in feel if you take weight off in this area.
The stock 19" lobster claws weigh 100lbs for a set of 4. I've dropped about 36lbs of weight with the PCCB's and will drop another 38lbs with new wheels, tires and lugs when they arrive. The net total reduction of approximately 74lbs should be the rough equivalent of removing 500lbs of static weight from the car. I'll report more when they arrive and I have some miles on them.
Dan - I agree with you. I had my 295 rear tire off due to a flat a week ago and the size of these wheel/tires is simply astonishing. The new ones will be 315/30/18 so they will look even more massive and provide astonishing grip, I'm sure.
MC
09-26-2006, 02:14 PM
#9
Id guess closer 70lbs per corner............ the f110's should take alot of unsprung weight off each corner.. i think the rears come in at 20lbs for rim. with tire should be closer to 50-55lbs.
09-26-2006, 02:59 PM
#10
Poseur
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Wow,--did I generate some interest here!
Here's what I finally got for numbers when I got a proper scale working for me:
Fronts (Bridgestones on 8.5 x 19 XRRs) balanced with TPMS: 42.5
Rears (Bridgestones on 11.5 x 19 XRRs) balanced with TPMS: 50
Each lug bolt weights 3.3 ozs (the lock ones are 3.5).
I noticed with factory TPMS that each wheel has been balanced and the bulk of the weights are places 180 degrees opposite the tire valve.
Will post some pictures. These tires are HUGE.
Here's what I finally got for numbers when I got a proper scale working for me:
Fronts (Bridgestones on 8.5 x 19 XRRs) balanced with TPMS: 42.5
Rears (Bridgestones on 11.5 x 19 XRRs) balanced with TPMS: 50
Each lug bolt weights 3.3 ozs (the lock ones are 3.5).
I noticed with factory TPMS that each wheel has been balanced and the bulk of the weights are places 180 degrees opposite the tire valve.
Will post some pictures. These tires are HUGE.
09-26-2006, 03:56 PM
#13
Burning Brakes
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Originally Posted by H20NOO
The stock 19" lobster claws weigh 100lbs for a set of 4. I've dropped about 36lbs of weight with the PCCB's and will drop another 38lbs with new wheels, tires and lugs when they arrive. The net total reduction of approximately 74lbs should be the rough equivalent of removing 500lbs of static weight from the car. I'll report more when they arrive and I have some miles on them.
Regardless, I agree with you 110%. Good writeup, thanks for the wheel weight info.
-don
09-26-2006, 06:15 PM
#14
Here's an excerpt from some material DyMag sent me:
Dymag carbon/magnesium car wheels
The new carbon/magnesium wheels were developed by Dymag for performance cars to achieve new standards of performance by achieving very low wheel weights and moments of inertia whilst retaining great strength and rigidity with the flexibility needed for both road and track use.
The wheels are made of a forged magnesium hub, designed to reduce the normal cast magnesium porosity to zero. The hub is then fastened to a carbon fibre rim by special coated titanium fasteners. The carbon rim is made from a very special process, developed by Dymag in the UK, using a solid metal mould which ensures that the wheels are consistently made to a very close tolerance of accuracy straight from the tooling. This also gives a very high quality durable finish which is resistant to brake dust, salt, ultra violet and the usual forms of corrosion encountered by race and road cars. Carbon fibre in this form is not onIy very strong, but is also quite resistant to shock and thus will withstand potholes better than magnesium. It will not shatter catastrophically as some have predicted – this is why carbon is used in formula one chassis and aeroplane wings.
The low weight but high stiffness of carbon fibre gives a very light weight rim to the wheel, significantly reducing the moment of inertia. This saves a considerable amount of power in turning the wheel. Consider that a standard Porsche 18” wheel weighs about 14kg, the Dymag carbon/magnesium equivalent weighs around 6kg saving about 32kg per car.
The effect on the car however, is more than the static weight saving. The moment of inertia calculation is based on the ratio of the mass multiplied by the square of the radius, meaning that as the diameter of the wheel increases then the greater the energy consumption of increased weight becomes. Therefore with the Dymag carbon/magnesium wheel the much reduced rim weight has the effect of at least 5 times the static weight reduction, meaning that the feel on the car performance is of taking out 2 large adult passengers!!
The effect of carbon/magnesium wheels when fitted to the car is to reduce the gyroscope effect of the wheel this gives the following effects:
1. Improved acceleration
2. Improved braking, reduced stopping distance
3. Lighter, sharper steering
4. Allows for softer damper settings giving more tyre contact & therefore better grip.
5. Tyre temperatures are more stable
6. improved wheel & tyre balancing
---- END OF EXCERPT ----
I haven't seen a standard formula but I'm guessing between 4-6X the effect of static weight removal. Keep in mind the benefits are greatest furthest from the hub so weight reduction at the wheel rim and tire tread will have far more positive impact than the same weight reduction at the hub or rotor carrier (hat). That's why 20" and larger wheels just suck the life out of a car or SUV. These SUV's running around on 24" wheels now have a hell of a time stopping without larger brakes. You push all that mass out so far from the hub and it's a bear accelerating and deccelerating it. Since the tire tread will always be at the edge, the closer you can move the weight of the rim to the hub, the more performance you can achieve. The area between the rim and tread is filled with air so it has no impact.
The weights quoted in the material from DyMag are not quite accurate. In my case, the standard 19" Porsche 997 S wheels weigh:
8x19" 22 lbs. 4 oz.
11x19" 27 lbs. 12 oz.
... ...........................EXACTLY 100lbs for the set.
The DyMags I purchased weigh:
8.5x18" 14lbs. 3 oz.
11x18" 17lbs. 2 oz.
...............................or, 62lbs 10 oz. for the set for a total savings of 37lbs 6 oz or 17kg (not 32kg as indicated above).
As an added point, I was disappointed to learn that the PCCB option on the 997 is not the same as the PCCB option on the GT3 and Turbo. Both of those get larger rotors and aluminum hats. The 997 PCCB has stainless steel hats I'm told and looking at them has me believing it.
The 18" tires will weigh 1lb more each in the rear and 2lbs more each in the front but that is more than offset by the lighter wheels. In total, the net loss will be about 75lbs between PCCB, wheels and lugs and that is very significant. Especially considering Porsche wheels are already very lightweight relative to similar wheel sizes from other manufacturers. Think of it this way.. Imagine a 75lb bag of cement attached to an axle. How much horsepower is consumed accelerlating it to 100mph in 10 seconds, and how much heat is generated slowing it down in 5?
MC
Dymag carbon/magnesium car wheels
The new carbon/magnesium wheels were developed by Dymag for performance cars to achieve new standards of performance by achieving very low wheel weights and moments of inertia whilst retaining great strength and rigidity with the flexibility needed for both road and track use.
The wheels are made of a forged magnesium hub, designed to reduce the normal cast magnesium porosity to zero. The hub is then fastened to a carbon fibre rim by special coated titanium fasteners. The carbon rim is made from a very special process, developed by Dymag in the UK, using a solid metal mould which ensures that the wheels are consistently made to a very close tolerance of accuracy straight from the tooling. This also gives a very high quality durable finish which is resistant to brake dust, salt, ultra violet and the usual forms of corrosion encountered by race and road cars. Carbon fibre in this form is not onIy very strong, but is also quite resistant to shock and thus will withstand potholes better than magnesium. It will not shatter catastrophically as some have predicted – this is why carbon is used in formula one chassis and aeroplane wings.
The low weight but high stiffness of carbon fibre gives a very light weight rim to the wheel, significantly reducing the moment of inertia. This saves a considerable amount of power in turning the wheel. Consider that a standard Porsche 18” wheel weighs about 14kg, the Dymag carbon/magnesium equivalent weighs around 6kg saving about 32kg per car.
The effect on the car however, is more than the static weight saving. The moment of inertia calculation is based on the ratio of the mass multiplied by the square of the radius, meaning that as the diameter of the wheel increases then the greater the energy consumption of increased weight becomes. Therefore with the Dymag carbon/magnesium wheel the much reduced rim weight has the effect of at least 5 times the static weight reduction, meaning that the feel on the car performance is of taking out 2 large adult passengers!!
The effect of carbon/magnesium wheels when fitted to the car is to reduce the gyroscope effect of the wheel this gives the following effects:
1. Improved acceleration
2. Improved braking, reduced stopping distance
3. Lighter, sharper steering
4. Allows for softer damper settings giving more tyre contact & therefore better grip.
5. Tyre temperatures are more stable
6. improved wheel & tyre balancing
---- END OF EXCERPT ----
I haven't seen a standard formula but I'm guessing between 4-6X the effect of static weight removal. Keep in mind the benefits are greatest furthest from the hub so weight reduction at the wheel rim and tire tread will have far more positive impact than the same weight reduction at the hub or rotor carrier (hat). That's why 20" and larger wheels just suck the life out of a car or SUV. These SUV's running around on 24" wheels now have a hell of a time stopping without larger brakes. You push all that mass out so far from the hub and it's a bear accelerating and deccelerating it. Since the tire tread will always be at the edge, the closer you can move the weight of the rim to the hub, the more performance you can achieve. The area between the rim and tread is filled with air so it has no impact.
The weights quoted in the material from DyMag are not quite accurate. In my case, the standard 19" Porsche 997 S wheels weigh:
8x19" 22 lbs. 4 oz.
11x19" 27 lbs. 12 oz.
... ...........................EXACTLY 100lbs for the set.
The DyMags I purchased weigh:
8.5x18" 14lbs. 3 oz.
11x18" 17lbs. 2 oz.
...............................or, 62lbs 10 oz. for the set for a total savings of 37lbs 6 oz or 17kg (not 32kg as indicated above).
As an added point, I was disappointed to learn that the PCCB option on the 997 is not the same as the PCCB option on the GT3 and Turbo. Both of those get larger rotors and aluminum hats. The 997 PCCB has stainless steel hats I'm told and looking at them has me believing it.
The 18" tires will weigh 1lb more each in the rear and 2lbs more each in the front but that is more than offset by the lighter wheels. In total, the net loss will be about 75lbs between PCCB, wheels and lugs and that is very significant. Especially considering Porsche wheels are already very lightweight relative to similar wheel sizes from other manufacturers. Think of it this way.. Imagine a 75lb bag of cement attached to an axle. How much horsepower is consumed accelerlating it to 100mph in 10 seconds, and how much heat is generated slowing it down in 5?
MC
09-26-2006, 08:53 PM
#15
Poseur
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Thee PCCB option on the 997/997S probably is the same as the late 996-based GT3s but with the second generation rotors. (They carry a 996 part number).
Your wheel research is excellent,--your weights are getting down to the older (and much smaller) forged Fuchs aluminum alloy wheels of yesteryear.
Your wheel research is excellent,--your weights are getting down to the older (and much smaller) forged Fuchs aluminum alloy wheels of yesteryear.