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My apologies Jim. I was too vague. They can be bought from Dundon or Supreme however it seems they are hard to get right now. They are light strong and modeled after BBS race wheels. Best Josh
Sorry to the OP for veering off topic to the original purpose of this post
My opinion on 245/325 choice and how it affects the balance, is that if one have their car setup perfectly to the balance that they want on 235/305 and then they switch to 245/325 without making any suspension setup adjustments(sway bar setting, rake, camber, toe, caster, track width, damping rate change, spring rate change) then it will push when driven at or near the limit of grip. The good thing is 997 GT3's have a lot of the suspension adjustments. And plenty of aftermarket or factory motorsport solutions for even more adjustments. For example, one of the adjustments that's often overlooked is front track width because rotating the front camber plates to full negative camber position is a popular thing to do to get more negative camber. By doing so, and by setting the strut tower slots to full inward the front track width is reduced by as much as 32mm relative to the same about of camber degrees with camber plates in original position and in the middle of strut tower slots. By going with the latter method, lengthening the LCA for camber instead of pulling everything inward at the top, this will increase high speed front grip. Another example, this is a factory setup example, the .2RS is factory equipped with more rake and stiffer rear sway bar than .1RS. Another example, some of drivers may have DSC products, which helps because the active damping commands changes to the grip(g-force).
I think that's what my idiot mind was attempting to say in my first post. That plus much heavier tires in the back. I haven't weighed any recently but you can feel it. The forged BBS help with the weight. Sorry Jim apparently the BBS are not available until December unless one off our friends wants to sell a set However as we know 325s do fit. Josh
Here's my NB car with 245/325 Cup 2's and cheap OZ wheels(19x8.5 ET53 front / 19x12 ET68 rear, no OEM rear spacers). These are my street, wet track, and "I don't feel like switching over" wheel & tire set.
PS- Thank you to gt2-josh for hooking me up with the rear wing end plates!
PSS- I don't shop at that store in the background...just happened to be at that parking lot for coffee.
Sorry to the OP for veering off topic to the original purpose of this post
My opinion on 245/325 choice and how it affects the balance, is that if one have their car setup perfectly to the balance that they want on 235/305 and then they switch to 245/325 without making any suspension setup adjustments(sway bar setting, rake, camber, toe, caster, track width, damping rate change, spring rate change) then it will push when driven at or near the limit of grip. The good thing is 997 GT3's have a lot of the suspension adjustments. And plenty of aftermarket or factory motorsport solutions for even more adjustments. For example, one of the adjustments that's often overlooked is front track width because rotating the front camber plates to full negative camber position is a popular thing to do to get more negative camber. By doing so, and by setting the strut tower slots to full inward the front track width is reduced by as much as 32mm relative to the same about of camber degrees with camber plates in original position and in the middle of strut tower slots. By going with the latter method, lengthening the LCA for camber instead of pulling everything inward at the top, this will increase high speed front grip. Another example, this is a factory setup example, the .2RS is factory equipped with more rake and stiffer rear sway bar than .1RS. Another example, some of drivers may have DSC products, which helps because the active damping commands changes to the grip(g-force).
Josh, I looked into the wheels and found the same thing as you are saying. Thanks for the info, Tom. Since you are well aware of my modifications (I have driven this very patient man to drink with all my questions over the past couple years), is there anything further I need to do to upsize to the .2 sizes? For others unaware, I have the Tractive/DSC setup, full RSS Tarmac Series including engine and trans mounts, GT2 sway bars front and rear, oem wheels and MPSS tires - all mounted on a 2007 RS running standard ride height. We have previously discussed the stability issues with the more track-specific alignment specs, and my current alignment (factory specs with slightly more camber) seems much more straight-line-stable (especially in the firmer of the two DSC modes). Would I need to change this further for the larger tires? When you say the .2RS has more "rake" are you referring to caster or camber? I am by no means as talented as many posters on this forum, but when entering a sharp (90 degree) lower-speed (45-60mph entry speed) turn quickly, it will push somewhat violently. If I had to describe what is happening, the front end first pushes slightly, then once it grabs, it gives a 'bouncy' sensation in the front end which feels as though the car is either bouncing off the shock rubber stops, or the tires are slipping, regripping, then slipping again in a cyclical pattern through the apex of the turn. I have practiced on keeping the weight more on the front end as I enter the corner to assist in minimizing this, but it is possible that my lack of sufficient driving skill to maintain a proper front-end weighting throughout the entire turn, is the cause. My end-goal is a more planted front end at entry through mid corner with the pushing more linear and controlled, and occurring at a higher loading (speed).
When you say the .2RS has more "rake" are you referring to caster or camber?
No. Rake is the angle of the car's chassis. It is a function of the difference between the car's front ride height and the rear ride height.
Raising the rear or the lower the front increases the rake. The purpose of more rake is to put more static load to the front to increase front grip. Too much rake will make the car loose!!!
On GT3's the rake is more commonly expressed by millimeters instead of angle.
997.1 RS factory ride height is 108/133mm so the rake is 25mm.
997.2 RS factory ride height is 102/137mm so the rake is 35mm
997.2 RS 4.0 factory ride height is 102/142mm so the rake is 40mm.
You can use these rake numbers as some sort of guideline.
Originally Posted by HarmonyJim
when entering a sharp (90 degree) lower-speed (45-60mph entry speed) turn quickly, it will push somewhat violently. If I had to describe what is happening, the front end first pushes slightly, then once it grabs, it gives a 'bouncy' sensation in the front end which feels as though the car is either bouncing off the shock rubber stops, or the tires are slipping, regripping, then slipping again in a cyclical pattern through the apex of the turn. I have practiced on keeping the weight more on the front end as I enter the corner to assist in minimizing this, but it is possible that my lack of sufficient driving skill to maintain a proper front-end weighting throughout the entire turn, is the cause. My end-goal is a more planted front end at entry through mid corner with the pushing more linear and controlled, and occurring at a higher loading (speed).
Personally I don't drive on public roads in this manner nor do I condone... But for the purpose of armchair evaluation, sounds like corner entry speed is too high(for those tires), causing tire chatter. Possible fixes are:
Reduce entry speed and focus more on exit (driver)
Do a quick "open the wheel" (driver)
Slight adjustment to throttle (driver)
Adjust the line (driver)
Put on wider and/or gripper front tires (car)
Increase rake (car)
Widen front track width (car)
Lower front tire pressure, some time raising the front tire pressure helps if the tires are aged out (car)
Add front toe-out, which you have tried but did not prefer how toe-out felt on straight (car)
Soften front sway bar or stiffen rear sway bar (car)
Less rear toe-in to let the car rotate (car)
Originally Posted by HarmonyJim
My end-goal is a more planted front end at entry through mid corner with the pushing more linear and controlled, and occurring at a higher loading (speed).
There is an optimum entry speed for every turn and for every tire size/compound. It is very possible to over drive the front tires. And there are uncontrolled variables on public roads that changes the grip level of the road surface so there's no definitive answers, but doing or more of the above may help given the uncontrolled variables remain somewhat close. My armchair hypothesis for the car would be to put 245/325 extreme performance summer tires on and increase the rake to be closer to .2 RS. Please keep in consideration that front tire chatter may be preventing something worst to happen.
The toe has to be reset because changing ride height changes the toe.
I'd suggest spitting the difference between .1RS and .2RS rake, which would be 5mm.
You can raise the rear by 5mm, or lower the front by 5mm, or do 3mm here 2mm there as long as end up to be 5mm of rake increase.
To make things easier you can go 6mm instead of 5mm since 6mm is equal to 4 turns of the adjuster.
As for the toe, perhaps try zero front toe, +1.5mm rear toe per side.
Yes, Tractive shocks are coilovers, they have a lot of ride height adjustability. Each turn of the adjuster is 1.5mm.
Here's a demo video- https://www.youtube.com/watch?v=NKyJ0ylzo6Y
The toe has to be reset because changing ride height changes the toe.
I'd suggest spitting the difference between .1RS and .2RS rake, which would be 5mm.
You can raise the rear by 5mm, or lower the front by 5mm, or do 3mm here 2mm there as long as end up to be 5mm of rake increase.
To make things easier you can go 6mm instead of 5mm since 6mm is equal to 4 turns of the adjuster.
As for the toe, perhaps try zero front toe, +1.5mm rear toe per side.
Tom the differences between .1 vs .2 is 10mm as you said before :
On GT3's the rake is more commonly expressed by millimeters instead of angle.
997.1 RS factory ride height is 108/133mm so the rake is 25mm. 997.2 RS factory ride height is 102/137mm so the rake is 35mm 997.2 RS 4.0 factory ride height is 102/142mm so the rake is 40mm. You can use these rake numbers as some sort of guideline.
thanks, I misunderstood. I thought that you meant rake :
997.1 RS factory ride height is 108/133mm so the rake is 25mm. 997.2 RS factory ride height is 102/137mm so the rake is 35mm
than rake .2rs 35mm- .1 rs 25mm rake = 10 mm defferences
rake = difference of hight between rear and front
you said 5 mm:
"The toe has to be reset because changing ride height changes the toe. I'd suggest spitting the difference between .1RS and .2RS rake, which would be 5mm. You can raise the rear by 5mm, or lower the front by 5mm, or do 3mm here 2mm there as long as end up to be 5mm of rake increase. To make things easier you can go 6mm instead of 5mm since 6mm is equal to 4 turns of the adjuster."
I had 245/35/19 and 325/30/19 and no problem. I do not know only it is improvment because I drive the same lap times despite of some improvments. Maybe 325 are to heavy for long straights. the gt3s 997.2, 991.1/2 have 305 and lots of power more.
and this time I started to have abs problem. But Ic hange pccb discs for steel ones (pfc -front). Does anyone knows hould I reprogram brake pressure for steel ones?
Again, resurrecting this thread. I'm hoping to get tires in the next couple of weeks but wanted to discuss what alignment set-up. From my post last year it seems to have gone off the rails. 1yr later I wanted to see if anyone had suggestions or perhaps had feedback on the set-up for the tire combo below on an 997.1 RS
What alignment & suspension set-up for street spirited driving? 325 245 315 245 325 255
05-28-2019, 12:37 PM
However as we know 325s do fit. Josh
