991 20" Rims
03-12-2016, 11:46 AM
#32
Ok ok nuff with the he said she said...... You can fit 991 20' wheels on a 997 the ride comfort will improve, there is no difference in the rubber profile from a 19' wheel, fronts 35' rears 30' and on a 20' wheels, fronts 35' rears 30' profile, only the rims are bigger from 19' to 20 inches, now, I think the ride is better because I believe the tire walls are stiffer as I have noticed a more comfortable damping feel on bumps and potholes, so an improvement to the 19s rubber, there are some right fools out there 'about the ride will suffer, where do these people come from with their opinions' do your homework then make a valuable opinion, so others can be informed.... Ask any 991 driver if the ride in harsh and I don't think Porsche would make it next gen 911 a worst and uncomfortable ride do you ....
Now, as for 18' for track I can't see the logic in this but that's another bag of weed to smoke haha I don't smoke ... Moving on ,,,
so you are thinking of going BIG, good boy or girl, here the pros and cons if you get the right offset wheels anything is possible I have a slim body 997 Carrera S running 991 20' wheels ,,, rubber boots 245-35-20 rims 8.5j / 20' offset 51' that the front; now the only problem with the front are the 245 tires with the standard Spring support touch, so to get out of jail, you would need to replace the tires to the 997 standard 235-35-19 to stop the rubbing or add a 5mm spacer at front but this pushes the rubbers out pass the arches this will effect cornering speeds,,,,
the best solution would be to upgrade your suspension support to coilovers springs and it's a win win situation all the way to the bank, you can keep the 245 rubbers without spacers giving you a wider track at stock heights or you have the option to lower your car but not as low as the black car above that's too much and the car will look slam, get all the wheels aligned and they will be no rubbing.... My 991 rears rubbers are 295-30-20 rims 11j / 20 offset 52' nothing to say here they fit no spacers required but you know, there room for a 21' rims here, 991 GT3RS anyone hmmmmm ......
P.s.....Porsche wouldn't give the 991 GT3RS MONSTER 20' front and 21'at the rears for track days 'IF' 18' wheels was the only option for track Manoeuvring, you may as well add skateboard kryptonic wheels to your Porsche the RED ONES not the Green or blue MMMMMM
03-12-2016, 11:55 AM
#33
Your right. This is a Rennlist.
The correct response is don't do it. It may put more stress on the IMS bearing and cause it to fail. Or worse could kick up extra rubber that would get into the engine and cause bore scoring.
The correct response is don't do it. It may put more stress on the IMS bearing and cause it to fail. Or worse could kick up extra rubber that would get into the engine and cause bore scoring.
The following 2 users liked this post by dgjks6:
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03-12-2016, 12:15 PM
#35
Rennlist Member
I think these OEM 991 wheels look great on the 997 w/ aero too.
03-12-2016, 12:42 PM
#36
So much I could say...
I'll offer one positive of the larger diameter. A smoother ride. I'm being serious. A larger diameter wheel rolls over obstacles more easily. Think monster truck and imagine the size curb it could go over as compared with a 19" 997 wheel.
I'll offer one positive of the larger diameter. A smoother ride. I'm being serious. A larger diameter wheel rolls over obstacles more easily. Think monster truck and imagine the size curb it could go over as compared with a 19" 997 wheel.
03-12-2016, 01:23 PM
#37
Rennlist Member
Originally Posted by JAGMAN1
So much I could say...
I'll offer one positive of the larger diameter. A smoother ride. I'm being serious. A larger diameter wheel rolls over obstacles more easily. Think monster truck and imagine the size curb it could go over as compared with a 19" 997 wheel.
I'll offer one positive of the larger diameter. A smoother ride. I'm being serious. A larger diameter wheel rolls over obstacles more easily. Think monster truck and imagine the size curb it could go over as compared with a 19" 997 wheel.
03-12-2016, 03:17 PM
#38
For more than 50 years Porsche increased WHEEL diameter while keeping TIRE diameter CONSTANT. Commonly called plus-sizing, this is what everyone thinks of when they talk about the 991.
Well, this is different. For the first time- EVER- Porsche did not PLUS-size http://www.tirerack.com/tires/tirete....jsp?techid=25 they UP-sized! Instead of the wheel diameter increasing while tire diameter stayed the same, now with the 991 for the first time ever they increased BOTH!
Not just one but several significant advantages arise from this one change.
1. Decreased rolling resistance. A larger tire rolls over bumps more easily. This also contributes to a smoother ride.
2. Increased sidewall height. The sidewall is the first part of the suspension to absorb bumps. Again, improved ride. Rims better protected from bumps.
3. Increased stability. The shape of the tire patch affects responsiveness and stability. http://www.tirerack.com/tires/tirete....jsp?techid=10
4. Increased grip. Since they did not reduce width but increased length the tire patch just got bigger.
These may not sound like much but they are, and they really add up. There's a recent video where AP talks about this and briefly shows a comparison of the tire patches with something like a 23% increase. The tire only got about 5 or 10% wider, so therefore at least half the increase came from the larger diameter.
Against all this the only real disadvantages are weight and effective gearing- both of which are negated by Porsche increasing horsepower at the same time.
03-12-2016, 04:10 PM
#39
Ok. So back to my question. Does putting a bigger diameter tire hurt anything? I have read a bunch of people say yes it does. But no specific reason why. And no stories if I put bigger tires on my car and it broke. So besides the speedo/odometer being off, what else?
03-12-2016, 04:43 PM
#41
Rennlist Member
So, this means that there will be more wear on bushings, dampers and springs. How much? I don't know. I would say negligible but it has to happen.. because physics.
This is also assuming rotational inertia will be the same. In reality it will most likely be better (closer to the center of the wheel) with less rubber on the 20". So, that's a plus for acceleration though it will very very small and likely immeasurable.
...... That should read .... you would need to replace the tires to the 997 standard 235-35-20 to stop the rubbing... Sorry NOT 19' ERROR
03-12-2016, 05:34 PM
#43
That's not what I am asking. I am asking if you do what this guy did, put 991 wheels and tires on the car. They are bigger. The tire diameter us bigger. That looks great. And you have all the advantages of a bigger tire.
So besides the speedometer being off, what are the other provable issues. I hear people say the car was designed around a different size tire, and not counting extreme performance, what are the issues?
Again, I am talking about what the previous poster did, putting 991 wheels and tires on the car.
So besides the speedometer being off, what are the other provable issues. I hear people say the car was designed around a different size tire, and not counting extreme performance, what are the issues?
Again, I am talking about what the previous poster did, putting 991 wheels and tires on the car.
03-12-2016, 05:51 PM
#44
My car use to run on 305 C4s sections tires at the rear with a 5mm up front to help the understeer at fast bends then I pushed it out to 7mm spacer, it's been 5years of fast driving and not a problem with my axle or engine... It just wheels and tires and they go round and round .... At some point things go wrong with your car at no fault of your own, you can deal with it with a replacement part, or sit and cry, and never take your car on a modified adventure because the boys at Porsche HQ say No you can't do that to your 997 ,,, it's just a car like any other ,,, I know mods are not for everyone and I get that , but Porsche make mods and we bend over to get them ,, ( The black edition the UK Edition the Mayfair, GTS and now the R) I'm just creating my own personal edition the LE MANS 24 remember where you saw it first HAHAHAHAHA.
