utkinpol

i know (as I use it) that 265/35r18 fits in front but I am not sure if 265r19 will fit there. may be if you have smaller springs like I have with my JRZs, but with stock springs IMHO - unlikely. I would try to test fit it first. 245r19 should clear fine.

I will try to see if I can get cup 10" wide 18" rims fit my front without rolling up fenders. that should be fun.

FTS

It was really my pleasure, I hope you enjoy them at the track

Good luck with that one

utkinpol

yeah, probably will not work... but 9" with 265 clears fine and 275 is just .5" wider.
my front suspension is altered a bit to give more room there, so, will see.

atleung

No problem, Fatih. I am overseas at the moment returning 1/31. We can do it after I return. Al

aero997c2s

Toaster- When you and Al get together would you mind taking some shots of how his wheels fit on the regular 3 so we can see how much they do stick out it any. Plus I want to see those red wheels of his on a white car

audiophilitis

Somewhat related note...would 325/30/19 tires (stock RS rear tires) fit in a non-RS GT3 using stock non-RS wheels? In other words, using 325 instead of the 305 tires? If so, will this cause any speedo errors? TIA.

FTS

I'll certainly take pictures for fitment purposes, but I doubt we'll put on all four. I know his wheels look awesome, I am just excited that I'll be seeing them up close

the the RPM different is about 1.6% (778 vs 790), so there shouldn't be any issues. If I can put 265s up front, I'll be going with 325s in the rear depending on the track.

aero997c2s

Just one will do it for me. I've seen his wheels up close at and they look incredible. Always wondered how they'd look on my car and since yours is the exact same thing, well I can live with that.

utkinpol

it is pretty interesting that I am getting advices from some people who did quite extensive comparison of this subject to move as close to 'square' setup as possible - like 255/275 or even 235/255.

i personally would like to try 275/315 in NT01 perhaps as like a feel of staggered tires but trick is to make 275 fit in front. other option is 265/305. still it really feels counterintuitive to go with square setup on a 997 car...

FTS

I keep hearing more and more about square setup, but it just does not make any sense to me what so ever. This is a not a BMW, and unless you are running autoxes, why would you want such a lively backend?

I am sure I am missing some information that clouds my thinking, but with all that we know about 911 suspension, weight bias and on-track attitude, it does not compute for me.

Is there any data you can point us to from those people that has done "extensive comparison"? If data supports it, it is worth looking into researching the whys.

Edit:

After reading your other post on this, I understand it a little better. My opinion, with data yet to back it up yet, is maximizing front grip is essential on the 911 platform, hence my desire to be able to fit 265s. Because, I believe that if I can fit the largest possible tire in the front, it is going to be significantly less challenging to adjust the attitude of the car from one track to another using the A/R bars and tire pressure in the rear. I will most like start off with 305 in the rear, and if the A/R and tire pressures are not sufficient for my style of driving and tracks that I visit, then I'll move to 325s. But I'll have options.

IMHO, if the fronts are 235 or 245, there are much less options for vehicle attitude adjustments even at 305 rears.

Larry Cable

+1 with a 50/50 weight bias (and non adjustable sways) going for a "square" setup on a BMW (for example) makes perfect sense since this apparently dials out some of the understand (matching slip angles?)

Clear Porsche have also dialed in some understeer with their tyre choices that can be dialed out by narrowing the difference in slip angle between the front and rear ... my intuition is that if you go to far the car will be undrivable/dangerous ...

Also for the 997.2's the slip angles will (indirectly) be a component of the PSMs (SC) algorithms for determing its intervention, it is conceivable that you could end up causing PSM to intervene more by doing something like this ... note this would also be an issue on any PSM (SC) equiped car.

An interesting experiment (which I tried years ago in my '99 CS) is to dial the front SB to full hard and the rear to full soft ... try driving that around a track (make sure there are no hard things to hit) ... maybe better at an auto cross!

The result is something that Karl Malden and Michael Douglas would be proud to navigate around the "Streets of San Francisco" minus the cop tyres and the
obligatory hub cap that flies off ... not available in metallic "baby poo" brown.

I definitely think the cars can benefit from more rubber at the front, but I would be very hesitant to reduce the amount of rubber at the rear ... especially at a track with high speed corners! carpe diem!

Carrera GT

What are the widths of tires used on the Cup and RSR? I'm guessing around 12 inches in front and 13 inches in rear. Keep in mind the 60/40 weight and down-force affect the traction front and rear, also the front of the car acts not only as steering, but also as a lever force on the "pendulum" mass of the engine. Also, in braking and in acceleration, the rears usually work in concert -- they're also working together to make the car drive off the tangent at any instant on the arc of a turn, while the weight transfer means the "outside" front is doing disproportionately more work than the inside front, which is losing both weight and camber (or contact area) to give it a diminishing role in the various equations.

I don't think anyone is suggesting equal front and rear section widths, but the 911 today is not like the 911 of yesteryear.

Larry Cable

thats pretty much why I suggested larger at the front and not smaller at the rear

FTS

Yes, same here. I cannot imagine 'square' setup to work, but I think Utkinpol is suggesting reducing the tire width difference much more, so that they are as square as they can be on a 911. Less than 305 in the rear with ~360 hp going to them won't work IMHO. 325 in the rear with 245 in the front will only increase understeer with very little recourse. So, I think the best option is to start with 265s in the front with 305s int the rear (I do like slightly loose cars on high-speed corners), then I can make small adjustments with the chassis to balance it out. If I cannot, then move to 325 in the rear.

So, stock setup on regular 3 offers 70 mm difference front to back; option 1 with 265/305 combination would be 40 and 265/325 would be 60 mm, still better than stock config IMO, but gotta collect some data first If 265s are not available for some reason, than I will go with 245/305 combo

Carrera GT

I think 265/325 on a GT3 and 265/345 on the 3.8 RS works beautifully. 305 on the rear of a GT3 is great for learning to rotate the car, but it's not enough to get the power down and really lock up the rear and get out of the turns. In my humble.